Thatch control for cool-season lawn grasses such as bluegrass and tall fescue is usually done in the fall but now is the time we should perform this operation for warm-season turfgrasses such as bermudagrass and zoysiagrass. Because these operations thin the lawn, they should be performed when the lawn is in the best position to recover.  For warm-season grasses that time is June through July. Buffalograss, our other common warm-season grass, normally does not need to be dethatched.
 
When thatch is less than one-half inch thick, there is little cause for concern; on the contrary, it may provide some protection to the crown (growing point) of the turfgrass. However, when thatch exceeds one-half inch in thickness, the lawn may start to deteriorate. Thatch is best kept in check by power-raking and/or core-aerating. If thatch is more than 3/4 inch thick, the lawn should be power-raked. Set the blades just deep enough to pull out the thatch. The lawn can be severely damaged by power-raking too deeply. In some cases, it may be easier to use a sod cutter to remove the existing sod and start over with seed, sprigs or plugs.  If thatch is between one-half and a 3/4- inch, thick, core-aeration is a better choice.
 
The soil-moisture level is important to do a good job of core-aerating. It should be neither too wet nor too dry, and the soil should crumble fairly easily when worked between your fingers. Go over the lawn enough times so that the aeration holes are about 2 inches apart. Excessive thatch accumulation can be prevented by not overfertilizing with nitrogen. Frequent, light watering also encourages thatch. Water only when needed, and attempt to wet the entire root zone of the turf with each irrigation.
 
Finally, where thatch is excessive, control should be viewed as a long-term, integrated process (i.e., to include proper mowing, watering, and fertilizing) rather than a one-shot cure. One power-raking or core-aeration will seldom solve the problem. (Ward Upham)

Soils are warm enough now that tomatoes can benefit from mulching though this practice may have to be delayed due to wet soils. Tomatoes prefer even levels of soil moisture and mulch provides such by preventing excessive evaporation. Other benefits of mulching include weed suppression, moderating soil temperatures and preventing the formation of a hard crust on the soil. Crusted soils restrict air movement into and out of the soil and slow the water infiltration rate.
 
Hay and straw mulches are very popular for tomatoes but may contain weed or volunteer grain seeds. Grass clippings can also be used but should be applied as a relatively thin layer – only 2 to 3 inches thick. Clippings should also be dry as wet clipping can mold and become so hard that water can’t pass through. Also, do not use clippings from lawns that have been treated with a weed killer until some time has passed. With most types of weed killers, clippings from the fourth mowing after treatment may be used. If the lawn was treated with a product containing quinclorac (Drive), the clippings should not be used as mulch. If the weed killer used has a crabgrass killer, it likely contains quinclorac. (Ward Upham)

Apple trees often produce excess fruit. Removing some of these extra fruits during the next three weeks is important. There can be two major benefits from fruit thinning. The first is to help ensure a return bloom for a good fruit crop next year. Apples produce fruit buds for next year's crop during June; the same time this year's fruit is maturing. Too many fruit this year leads to a lack of fruit bud development and a small crop next year. This leads to biennial bearing in which an apple tree produces a large crop one year and very few fruit the next. Thinning helps ensure that apples are produced each year.
 
The second benefit of thinning is to promote larger fruit on this year's crop. Generally, an average spacing throughout a tree of about 4 inches per fruit is sufficient for a good return crop next year, as well as a desirable size on the fruits to be harvested this fall. (Ward Upham)

Bacterial soft rot of iris causes a smelly and slimy rot of the leaves and rhizomes. Leaves often separate easily from the rhizome. Heavily infested plants may die. Though most often associated with iris borer, environmental damage can also provide an entry point for this disease.
 
Rhizomes that show extensive signs of damage should be discarded. If there is a plant that has special value, you may wish to try to save it. The American Iris Society suggests using a spoon to remove all infected tissue. Then, allow the rhizome to dry in the sun. Finally, use a chlorine based cleanser to powder the wound. Dousing in place with Dial antibacterial soap (with triclosan) can be substituted for the chlorine based cleanser.
 
When dividing rhizomes from beds that have shown evidence of soft rot, disinfect the knife between cuts of even apparently healthy rhizomes with a 10% bleach solution or rubbing alcohol.
 
As mentioned previously, iris borer damage can provide a place of entry for this disease. To control iris borers, remove and discard dead leaves in the fall to eliminate a number of the iris borer eggs. Larvae can also be killed by hand in June by squeezing infested leaves in the vicinity of the injury. During division, borers in lightly infested rhizomes can be killed by poking them with a piece of wire. Borer control can also be achieved through the use of imidacloprid (Merit, Bayer All-In-One Rose & Flower Care, Bonide Systemic Granules, Hi-Yield Systemic Insect Granules) or through the use of the parasitic nematodes Steinernema carpocapsae or Heterorhabditis bacteriophora.
 
Imidacloprid should be used as a drench (directions on label) when the air temperature reaches 70 degrees two days in a row.
 
The parasitic nematodes must be applied when the soil temperature is above 50 degrees F. Use 1 quart water/nematode mix per square foot to allow the nematodes to swim to the pest.
 
Steinernema carpocapsae gave better control (100%) than Heterorhabditis bacteriophora (87%) in research conducted by the University of Maryland. (Ward Upham)

Spirea aphid (Aphis spiraecoa)  is present feeding on spirea (Spiraea spp.) plants in landscapes. Spirea aphid colonies aggregate on terminal growth and their feeding causes leaf curling and stunted plant growth. Spirea aphids prefer to feed on stems and leaf undersides of succulent plant growth. All mature aphids are parthenogenic  (reproduce without mating) with females giving birth to live nymphs, which themselves are females. Eggs are laid on bark or on buds in the fall by wingless females after having mated with males. Eggs hatch in spring, and young nymphs develop into stem mothers that are wingless. Spirea aphid females are pear-shaped and bright yellow-green. Stem mothers reach maturity in about 20 days. Each spirea aphid female can produce up to 80 offspring or young females.
 
Although the aphids produce honeydew (sticky, clear liquid), continual rainfall will wash the honeydew off plants.  In the summer, both winged and non-winged aphids may be present. The winged forms usually appear when conditions become crowded on infested plants, in which they migrate to a more suitable food source such as another spirea plant to start another colony.
​
Heavy rainfall and strong winds will dislodge spirea aphid populations  from plants onto the ground, where they eventually die. Frequent applications (twice per week) of forceful water sprays will quickly remove spirea aphid populations without disturbing natural enemies such as parasitoids and predators.  They have a number of natural enemies including ladybird beetles, green lacewings,  and hover flies that may help to regulate spirea aphid populations. Spirea aphids are, in general, exposed to regular applications of pesticides such as insecticidal soaps (potassium salts of fatty acids) and/or horticultural oils (petroleum, mineral, or neem-based) that may be effective in suppressing populations of spirea aphid. These pesticides have contact activity only, so thorough coverage of all plant parts is important. Furthermore, these pesticides are generally less harmful to natural enemies compared to conventional pesticides.  (Raymond Cloyd)

Gregg Eyestone, Horticulture Agent from Riley County, has put together a nice chart that covers sidedressing nitrogen on annual flowers, certain perennial flowers, vegetables and various small fruit. Sidedressing (also called topdressing) is applying nitrogen fertilizer as plants are growing to give them an extra boost. Done correctly, sidedressing can improve vegetable, fruit and flower production. Gregg lists the crop, the amount of fertilizer needed, and suggested time of application. Rates are given for ammonium sulfate, urea and blood meal. You may find the chart at  http://tinyurl.com/hxtgres (Ward Upham)

Tree squirrels can cause a couple types of tree damage. Most commonly they clip the tips of branches. The length of severed branches is often 2 to 3 feet though they can be longer or shorter. When squirrels snip off a branch, they cut it at about a 45-degree angle and the cut is rather tattered. This is a nuisance type of damage and normally does not harm the health of the tree.
 
More serious damage is caused when squirrels strip the bark off of limbs or rarely, the trunk. Wounds can be quite large and the squirrel can effectively girdle the branch by removing all the bark completely around the circumference. Branches girdled in this way will die and the tree may be ruined if those branches are major.
 
Why squirrels do this is still a bit of a mystery. Some people think it is simply a means to sharpen their teeth or that they are seeking nesting material or water. Other people think that there are certain squirrels that are high-strung and cause this damage out of nervous energy. If the damage is limited to snipping the ends off of branches, it is probably best to ignore the activity as the tree suffers little harm. But if real damage is occurring due to extensive bark removal, try feeding and watering them. If that doesn’t work, control may be necessary. Fox and gray squirrels are game animals and can be hunted in season where it is legal and safe to do so. They can also be trapped and moved away from the area they are causing damage. For more information on control, see  http://www.bookstore.ksre.ksu.edu/pubs/L863.pdf . (Ward Upham)

Waterlogged soils push out oxygen that roots need to survive. Every living cell in a plant must have oxygen or it dies. Some plants have mechanisms to provide oxygen to the roots even under saturated conditions but most of our vegetables and flowers do not. The longer these plants are subjected to saturated soils, the more likely damage will occur.
 
Usually, as long as water drains away within 24 hours, the impact on plant health is minimal. However, shallow, stagnant water under hot, sunny conditions can literally cook plants, reducing survival time to as little as a few hours.
 
Vegetables: What about safety regarding eating produce from a garden that has been flooded? Standing water should not cause a safety problem as long as the aboveground portions of the plant remain healthy. Do not use produce from plants that have yellowed. Also, using produce flooded with water contaminated with sewage (lagoon) or animal manure can also be dangerous.
 
The safest approach is to discard all garden crops that have been in contact with such water. Certainly, leafy vegetables should always be discarded. However, you may eat fruit from such crops as tomatoes, peppers, eggplants, sweet corn, squash, cucumbers, and similar vegetables that develops after the waters have subsided as long as the fruit is not cracked or soft. Always wash vegetables thoroughly before eating.
 
Lawns: Under the cool conditions of early spring, turfgrasses can often survive several days of flooding. However, during hot, sunny conditions with shallow, stagnant water, lawns may be damaged quickly, sometimes in a few hours. This situation often occurs when shallow depressions in a lawn allow water to pool. Note such areas and fill in with additional soil once the waters have subsided.
 
Trees: Trees differ markedly in their ability to withstand flooding. Some trees have mechanisms in place to provide oxygen to the roots of plants with water saturated soils and others do not. However, most trees will maintain health if flood waters recede in 7 days or less. It also helps if water is flowing rather than stagnant as flowing water contains more oxygen. If the roots of sensitive trees are flooded for long periods of time, damage will occur including leaf drop, iron chlorosis, leaf curl, branch dieback, and in some cases, tree death. Another danger of flooding is the deposition of sediment. An additional layer of silt 3 inches or more can also restrict oxygen to the roots. If possible, remove deep layers of sediment as soon as conditions permit. This is especially important for small or recently transplanted trees.
 
Try to avoid any additional stress to the trees this growing season. Ironically, one of the most important practices is to water trees if the weather turns dry. Flooding damages roots and therefore the root system is less efficient in making use of available soil water. Timely waterings are vital to a tree’s recovery. Also be diligent in removing any dead or dying branches which may serve as a point of entry for disease organisms or insect pests. The following information on tree survival came from the US forest Service.
 
Trees Tolerant of Flooding: Can survive one growing season under flooded conditions. Red maple, silver maple, pecan, hackberry, persimmon, white ash, green ash, sweetgum, sycamore, eastern cottonwood, pin oak and baldcypress.
 
Trees Moderately Tolerant of Flooding: Can survive 30 consecutive days under flooded conditions. River birch, downy hawthorn, honeylocust, swamp white oak, southern red oak, bur oak, willow oak and American elm.
 
Trees Sensitive to Flooding: Unable to survive more than a few days of flooding during the growing season. Redbud, flowering dogwood, black walnut, red mulberry, most pines, white oak, blackjack oak, red oak and black oak.
 
After the Flood: Soils often become compacted and crusted after a heavy rainfall. This also can restrict oxygen to the roots. Lightly scraping the soil to break this crust will help maintain a healthy root system and therefore, a healthy plant. Be careful not to cultivate too deeply as shallow roots may be damaged. If you think the excessively wet weather will continue, bedding up the rows before planting even just a couple of inches, will improve drainage and allow for better aeration. (Ward Upham)
 
Contributors: Raymond Cloyd, Extension Entomologist; Ward Upham, Extension Associate

What do you do when the lawn can't be cut because of constant rain? The best thing to do is to set your mower as high as possible and bring it down in steps. It is always best never to take more than one third of the grass blade off at one time. If more is taken, the plant reacts by using stored energy reserves to quickly send up new growth. This reduces the amount of energy available for the plant to deal with stress or damage done by insects or disease. However, sometimes it is just not possible to keep the "one-third rule." In such cases, cut as high as possible even though it may mean you are cutting off more than one third of the blade. Bring the height down gradually by cutting more often and at progressively lower heights until you reach the target height. (Ward Upham)

​June is the time to fertilize warm-season lawn grasses such as bermudagrass, buffalograss, and zoysiagrass. These species all thrive in warmer summer weather, so this is the time they respond best to fertilization. The most important nutrient is nitrogen (N), and these three species need it in varying amounts.
 
Bermudagrass requires the most nitrogen.  High-quality bermuda stands need about 4 lbs. nitrogen per 1,000 sq. ft. during the season (low maintenance areas can get by on 2 lbs.). Apply this as four separate applications, about 4 weeks apart, of 1 lb. N per 1,000 sq. ft. starting in early May. It is already too late for the May application, but the June application is just around the corner. The nitrogen can come from either a quick- or slow-release source. So any lawn fertilizer will work.  Plan the last application for no later than August 15. This helps ensure the bermudagrass is not overstimulated, making it susceptible to winter-kill.
 
Zoysiagrass grows more slowly than bermudagrass and is prone to develop thatch.

Consequently, it does not need as much nitrogen. In fact, too much is worse than too little. One and one-half to 2 pounds N per 1,000 sq. ft. during the season is sufficient. Split the total in two and apply once in early June and again around mid-July. Slow-release nitrogen is preferable but quick-release is acceptable.  Slow-release nitrogen is sometimes listed as “slowly available” or “water insoluble.”
 
Buffalograss requires the least nitrogen of all lawn species commonly grown in Kansas. It will survive and persist with no supplemental nitrogen, but giving it 1 lb. N per 1,000 sq. ft. will improve color and density. This application should be made in early June. For a little darker color, fertilize it as described for zoysiagrass in the previous paragraph, but do not apply more than a total of 2 lb. N per 1,000 sq. ft. in one season. Buffalograss tends to get weedy when given too much nitrogen. As with zoysia, slow-release nitrogen is preferable, but fast-release is also OK. As for all turfgrasses, phosphorus and potassium are best applied according to soil test results because many soils already have adequate amounts of these nutrients for turfgrass growth. If you need to apply phosphorus or potassium, it is best to core aerate beforehand to ensure the nutrients reach the roots. (Ward Upham)

Fireblight is most common on ornamental pears, fruiting pears and apples. Symptoms of fireblight include blackened, blighted shoots scattered throughout the tree crown. The shoots may have the classic Shepherd's crook where the blighted tips bend downward. There may be small amber droplets of bacteria on the stem. This late in the season, antibiotic applications are not effective in controlling the disease. It is important, however, to control insects that may become contaminated with the bacterium and/or create wounds for infection.
 
During the summer, prune out the blighted tips during dry weather. Make your pruning cut 10 to 12 inches below the discolored area of the branch. Disinfect pruning equipment between cuts with rubbing alcohol or some other disinfecting agent. Some people prefer the ugly stub method and snap the branch off below the blighted area. This helps someone see at a glance where fireblight occurred in the tree and will facilitate follow-up pruning during the winter. (Ward Upham)

With all the concern with vein pocket gall, people will often become concerned with anything on a leaf that does not look natural.  However, many pin oak trees have a fuzz that is found between the mid-vein and side-veins on the bottom side of a pin oak leaf.  This fuzz is natural and is not a cause for concern.
 
Note that there are fuzzy galls that can infect a pin oak leaf but they are not limited to the “V” between the mid-vein and side-vein. Though these galls also do not cause significant harm, they are not natural to the leaf but are caused by an insect or mite.  (Ward Upham)

Watch for rust on hollyhock. This is the most common disease on hollyhock and can cause serious injury as leaves are progressively killed through the summer. Look for yellow spots on the surface of the leaves and orangish to brown pustules on the underside. Infections can also take place on stems and green flower parts. The first line of defense is to remove all hollyhock stalks, leaves and other debris in the fall and destroy them. Remove any infected foliage you see now. Just be sure the foliage is dry so you don’t spread the disease. Continue to remove diseased leaves as soon as they show spots. Try using a fungicide such as sulfur or myclobutanil (Immunox or Immunox Plus) to protect healthy foliage. Note that sulfur may burn leaves if the air temperature is over 85 degrees within 24 hours of application. Follow label directions for timing and rate. (Ward Upham)

If you had cucumbers or muskmelons that suddenly turned brown and died last year, you may have had a disease known as bacterial wilt. The cucumber beetle carries this disease. Once a plant is infected, there is no cure, so prevention is the key. Because cucumber beetles overwinter as adults, early control measures are essential. There are two types of cucumber beetles: striped and spotted. The striped cucumber beetle is the most common. The 1/4-inch-long beetles are conspicuously colored: black head and antennae, straw-yellow thorax, and yellowish wing covers with three distinct parallel and longitudinal black stripes. Young plants can be protected with row covers, cones, or other types of mechanical barriers. Edges must be sealed to ensure that the beetles do not find a place to enter. Plants will eventually outgrow these barriers, or they will need to be removed to allow insect pollination of the flowers. Apply insecticides before beetles are noticed in the planting. Continue to spray weekly throughout the season.
 
Homeowners can use permethrin (numerous trade names). Once plants have started flowering, spray in the evening after bees have returned to the hive. Check labels for waiting periods between when you spray and when the fruit can be picked. (Ward Upham)
 
Contributors:  Ward Upham, Extension Associate

Yellow nutsedge is a relatively common problem in lawns, especially in wet years or in lawns with irrigation. Although it looks much like a grass, it is a sedge. Unlike grasses, sedges have triangular stems, and the leaves are three-ranked instead of two-ranked, which means the leaves come off the stems in three different directions. Yellow nutsedge is pale green to yellow and grows rapidly in the spring and early summer. Because of this rapid shoot growth, it sticks up above the rest of the lawn only a few days after mowing. This weed is a good indicator of poor drainage, but it can be introduced into well-drained sites through contaminated topsoil or nursery stock. As with many weeds, nutsedge is less competitive in a dense, healthy lawn than in an open, poor lawn.
 
Nutsedge is difficult to control culturally because it produces numerous tubers that give rise to new plants. Pulling nutsedge will increase the number of plants because dormant tubers are activated. However, it is possible to control nutsedge by pulling, but you must be persistent. If you are, eventually the nutsedge will die out.
 
If you were going to treat with an herbicide, it would be better to leave the nutsedge plants undisturbed so the herbicide can be maximally translocated to the roots, rhizomes, and tubers. Several herbicides are available for nutsedge control. SedgeHammer, which used to be called Manage, is the most effective and safe for most turfgrasses. It is also the most expensive, but if an infestation is not too severe, one application should take care of the problem. The SedgeHammer label says to apply it after nutsedge has reached the three- to eight-leaf stage. Waiting until this growth stage apparently results in improved translocation of the active ingredient to the underground tubers and rhizomes. However, research has shown that the application should go down by June 21. If the initial spray is after June 21, mature daughter tubers may be stimulated to grow.
 
Small packages of SedgeHammer are available to homeowners. Using a non-ionic surfactant with the SedgeHammer will give better control. (Ward Upham)

We are starting to see anthracnose on sycamore. Anthracnose is a fungal disease favored by cool, wet weather. Young leaves may wither and turn black. On older leaves, look for brown areas that follow the major veins of the leaves. In some cases, the petiole (leaf stem) is infected, which causes leaf drop. The leaf may look perfectly fine, so look for browned areas on the petiole.
 
In severe cases, the tree drops heavily infected leaves and may be completely defoliated. Healthy trees will leaf out again in a few weeks. Defoliation this early in the year does not affect overall tree health. Trees have plenty of time to produce new leaves and make the energy reserves needed to survive the winter.
 
Other types of trees that are affected by anthracnose include birch, elm, walnut, oak and especially ash. Anthracnose seldom causes significant damage to trees in Kansas, so chemical controls are usually unnecessary. Also, fungicides do not cure infected leaves. Applying fungicides now will not help. (Ward Upham)

There has been growing interest in straw bale gardening. What better place to try this than in Kansas where straw is so abundant.  First, some pointers.
•  These are the “small” straw bales that are about 2 feet high and 3 feet long.
•  Place the bale on edge so the twine doesn’t rot.
•  Bales can be placed anywhere including concrete or asphalt.  Just make sure there is plenty of sun and watering is convenient
 
Bale Conditioning
•     Water the bales and keep them wet for 3 days.  The bale will start to heat up as it breaks down.
•     On days 4, 5 and 6, sprinkle fertilizer on the top of each bale with 1 cup of ammonium sulfate (21-0-0) or ½ cup of urea (46-0-0).  Water the fertilizer in.  This speeds the decomposition process.
•     On days 7, 8 and 9, continue to sprinkle fertilizer on each bale but cut the amount in half.
•     Stop fertilizing on day 10 but keep the bale moist.
•     Check for heat on the top of each bale for each day after day 10.  When the temperature drops to below 100, the bale can be planted.
 
Planting
•     Pocket Method: Make a hole for each plant several inches deep and fill with growing medium.
•     Flat Bed Method: Cover the top of the bale with 3 to 4 inches of growing medium.
•     The growing medium can be well-aged manure, compost or potting soil.
 
Number of Plants per Bale
•     Cantaloupe:                2
•     Cucumber:                 3-4
•     Peppers:                     3-5
•     Squash (winter)          2
•     Squash (summer)       2-3
•     Tomatoes                   2-3
 
Watering
Watering will be the most challenging aspect of management.  The straw will dry quickly.  A drip irrigation system on a timer can work well but may take some time to set up.  Gardeners may also use soda bottles or milk jugs to water by poking drip holes in the lid, filling with water and then turning upside down next to the target plant.
 
This information was taken from an excellent publication from Washington State University that includes much more detail as well as images.  See http://cru.cahe.wsu.edu/CEPublications/FS109E/FS109E.pdf .  (Ward Upham)
 
Contributors:  Ward Upham, Extension Associate

The Johnson County Extension Master Gardeners Public Garden Tour will be held May 20 and 21. Six private gardens will be open to the public. Each garden is unique and has something of interest for gardeners. For more information visit www.johnson.k-state.edu for more information

Sweet corn is one of those crops that is only "good" for a few days. If you want longer periods of production, consider staggering the planting. In other words, plant a small block, wait a period of time, and then plant the next block. Though it is tempting to follow a calendar schedule, such as planting a small block every week, it is better to use crop development as a trigger. If you plant on a calendar schedule, you may have noticed that later plantings often catch up with earlier ones. Instead, plant the next block of sweet corn when the previous one is one-half to one inch tall. (Ward Upham)

Some areas of Kansas have avoided late freezes resulting in a heavy fruit crop this year. At first glance, this might seem to be a good thing. But too many fruit can cause problems that should be alleviated with thinning. For example, a heavy fruit crop can interfere with fruit bud development this summer. This can result in a small to no crop next year. This problem most often appears with apples. Thus, thinning helps ensure that good crops are produced each year.

The second benefit of thinning is to promote larger fruit on this year’s crop. Fruit trees are limited in how many fruit they can mature. Too many fruit and fruit size goes down.

A third problem often caused by too many fruit is limb damage. Sometimes the weight of a maturing fruit crop can literally break branches. Thinning will help limit weight and preserve branches.

So how much thinning should we do? Thinning recommendations vary with the type of tree.

Guidelines for fruit spacing are as follows:
Apples and pears: 4 to 6 inches apart;
Peaches: 6 to 8 inches apart;
Plums and prunes: 4 to 5 inches apart;
Apricots: 2 to 4 inches between fruit.

​These are averages and so you may have several fruit clustered closer than this distance. As long as the average on the branch is close to the recommended spacing, the fruit should size well. Cherries are not thinned and can produce a full fruit load. (Ward Upham)

This is the time of year we normally start seeing damage from cabbage worms. The imported cabbage worm is usually the first cabbage worm species to appear and is a fuzzy, elongated green worm. Larvae come from eggs laid by the white butterfly often seen flitting around the plants.

Early control is essential to reduce injury. BT (Bacillus thuringiensis) and spinosad (Borer, Bagworm, Leafminer and Tent Caterpillar Spray; Captain Jack's Dead Bug Brew) are effective organic products that are labeled for this pest. BT can be found in Dipel, Thuricide and other similar materials. Direct sunlight deactivates BT quickly so it is helpful to spray late in the day or on a cloudy day.

​Conventional insecticides such as carbaryl (Sevin), malathion and methoxychlor are also effective but will kill natural enemies of these pests. Be sure to hit the underside of leaves where insects feed. Note that hitting the underside of leaves is easier when using a dust applied with a duster than when using a liquid spray. (Ward Upham)

This insect has been skeletonizing rose leaves in the Kansas City area. This is not a caterpillar but is the larva of a sawfly. Close examination of this small (½ inch) larva will reveal very fine, hairlike spines in clusters.

Young larvae will remove the green layer of a leaf leaving behind a clear material. As the larvae mature, they make holes in the leaf and eventually may consume all of the leaf but the major veins.

​Since these insects are not caterpillars (larvae of moths or butterflies), BT, found in Dipel and Thuricide will not be an effective treatment. However, a strong jet of water will dislodge the slugs and make it difficult for them to return to the plant. Other effective treatments include insecticidal soap, horticultural oils, spinosad (Fertilome Borer Bagworm, Leafminer and Tent Caterpillar Spray or Captain Jack’s Deadbug Brew) and permethrin (various trade names). (Ward Upham)

​Both the adults and the larvae of the ladybird beetle are beneficial and do not feed on plants but rather on other insects including aphids, mealybugs, whiteflies, scale insects and the eggs of various other insects. So if you see these insects, do not spray. The larval form looks like a very small alligator-shaped insect. Larvae are covered with spines, about 3/8-inch long, and black with orange markings. (Ward Upham)

Like last year, we are seeing a high number of oak galls this year, especially vein pocket gall on pin oak leaves. Vein pocket gall causes abnormal swelling of the leaf near the veins.

We also saw an outbreak of oak leaf itch mites last year. This mite feeds on the larvae of the midge fly that actually causes certain types of oak leaf galls. Though the marginal leaf gall is more commonly associated with oak leaf itch mite, the mite can also feed on the larvae in vein pocket galls. However, a large number of vein pocket galls do not necessarily mean we will have an outbreak of oak leaf itch mite like we had last year. This will be a “wait and see” situation.

Actually, there are hundreds of different types of galls, each of which is caused by a specific insect or mite. Insects that can cause different galls on oaks include tiny, nonstinging wasps and flies which cause abnormal growths to develop on the leaves, twigs or branches of oak trees. The galls caused by mites can include growths that are round, spiny, flattened, elongated or star-shaped.

Galls form in response to a chemical that the insect or mite injects into the plant tissue. Eggs laid by a mature female hatch into legless grubs around which the gall forms. The larvae feed, develop, and pupate inside these galls. The adults may emerge either the same season or may overwinter inside the gall depending on the life history of that specific insect.

Generally, these gall insects do not cause significant damage to their hosts, though some of the leaf galls can cause enough deformity to make a tree unsightly. Also, severe infestations of twig galls can cause twig dieback or, rarely, tree death. However, just because a twig is covered with galls does not mean it is dead. I have seen twigs that looked like a solid mass of galls leaf out in the spring.

Insecticide sprays applied when galls are noticed are ineffective because damage has already occurred. Also, larvae are unaffected because of the protection afforded by the gall. Insecticide sprays can kill emerging adult wasps and flies, but long emergence periods and short residuals of most contact insecticides make this impractical. Stem and twig galls can be pruned if this is deemed to be practical and necessary. Fortunately, natural predators and parasites usually bring these insects under control given a year or two. Therefore, the best option is usually to do nothing.

​What about the itch mites? More bad news. We have found nothing can effectively kill or repel these mites. The only means of defense is to avoid contact. (Ward Upham)

It is often helpful to set many houseplants outside for the summer so they can recover from the low light levels endured during the winter months. As soon as night temperatures stay consistently above 55 degrees F, houseplants can be moved to their summer home. Choose a spot that has dappled shade, is protected from the wind and is close to water. A porch or a spot that receives shade from trees or buildings will work well. Putting houseplants in full sun will cause the leaves to photooxidize or sunburn because the leaves have become adapted to low light levels inside the house. Where possible, sink the pots into the ground to help moderate root temperatures and reduce watering frequency.

​If you have a number of plants, dig a trench 6 to 8 inches deep (or deeper if you have larger pots) and long enough to accommodate all of your plants without crowding. Place peat moss under and around the pots. Peat moss holds water, helps keep the pots cool and reduces evaporation from clay pots. About every two weeks, rotate the pots a quarter turn to break off any roots that have penetrated the peat moss surrounding the pot and to equalize the light received on all sides of the pot. Water as needed. If the potting soil is dry a half-inch deep in the pot, it is time to water. (Ward Upham)

Rabbits in gardens are a perennial problem because of the wide variety of plants they can feed on. This time of year, they gravitate to young vegetables and flowers. But there are some vegetables that are rarely bothered including potatoes, tomatoes, corn, squash, cucumbers, and some peppers. The question is how do you protect other, more susceptible plants? Fencing provides a quick and effective control method. The fence does not need to be tall; 2 feet is sufficient for cottontails. But the mesh must be sufficiently fine (1 inch or less) so young rabbits will not be able to go through it. Support for the fence can be supplied by a number of products, but electric fence posts work well.

Often fencing is not an acceptable choice because it affects the attractiveness of the garden. Other ways to control rabbits including repellents, trapping and shooting. Repellents are often suggested for control but often do not last long and require frequent reapplication. Also, many are poisonous and cannot be used on plants or plant parts destined for human consumption. Live traps can be used to collect and move the rabbits to a rural area several miles from where they were trapped. A number of baits can be used to entice the rabbit to enter the trap including a tightly rolled cabbage leaf held together with a toothpick. However, rabbits often avoid baits if other attractive food is available.

Another possibility is to use a motion-activated sprinkler. These are attached to a garden hose and release a short burst of water when motion is detected. Contech, Orbit and Havahart are suppliers and each is advertised as protecting up to at least 1,000 square feet. Shooting is another possibility when it is safe and legal to do so. (Ward Upham)
​
Contributors: Ward Upham, Extension Associate

May is an excellent time to fertilize cool-season lawns such as tall fescue and Kentucky bluegrass if they will be irrigated throughout the summer. Non-irrigated lawns often go through a period of summer dormancy because of drought and do not need this fertilization.
 
May is a good time to fertilize because the springtime flush of growth characteristic of these grasses has tapered off, so the fertilizer you apply will be less likely to cause excessive shoot growth than if you fertilized at a full rate in April. Slow-release nitrogen sources are ideal. These nitrogen sources promote controlled growth, which is desirable as the stressful summer weather approaches. Relatively few fertilizers available to the homeowner supply ALL of the nitrogen in the slowly available form. But one such product that is widely available is Milorganite. Other such products available in the retail market include cottonseed meal, alfalfa-based fertilizers, and any other products derived from plants or animals. (Bloodmeal is an exception, and contrary to popular belief, the nitrogen it supplies is quickly available.) These products are all examples of natural organic fertilizers. They typically contain less than 10 percent nitrogen by weight, so compared to most synthetic fertilizers, more product must be applied to get the same amount of nitrogen. Translation: they are more expensive! Apply enough to give the lawn one pound of nitrogen per 1,000 square feet. For example, if the fertilizer is 6 percent nitrogen by weight, you will need to apply almost 17 pounds of fertilizer product per 1,000 square feet. Summer lawn fertilizers that contain at least a portion of the nitrogen as slow-release are fine to use as well. Be sure to follow label directions. If cost is prohibitive, you can use the less expensive quick-release (i.e., soluble) sources, but split the application into two doses as follows: apply enough to give the lawn 0.5 lb nitrogen per 1,000 square feet in May and again in early June. (Ward Upham)

Peach leaf curl is a fungus disease that causes developing peach leaves to become puckered and distorted and show a reddish-green hue. A similar disease called plum pocket may develop on American and sand hill plums. Plum pocket results in formation of distorted, light green, bladder-shaped fruit. Asian and European plums are not susceptible to the local strain of plum pocket. Unfortunately, it is too late to control these diseases with fungicides this year.
 
Trees that are severely infected with peach leaf curl are likely to lose many leaves. If trees are healthy, new leaves will grow. Indicators of a healthy tree are large, deep green leaves and last year's growth being at least 18 to 24 inches long. If these tree vigor indicators are not present, especially if there was only 12 inches or less of growth last year, then a fertilizer application would be helpful.
 
The fertilizer should be spread on the soil under the branch area. Apply 1 and 1/3 to 2 cups of a 13-13-13 fertilizer under the branch area. If a soil test indicates that only nitrogen is needed, use 1/3 to 1½ cups of nitrate of soda (16-0-0) instead of the 13-13-13. You may also substitute a high nitrogen fertilizer such as a 27-3-4, 30-5-4 or something similar for the 13-13-13, but use only half the amount used for nitrate of soda. The sooner fertilizer is applied, the more immediate benefit it will have in promoting new leaf growth. Both peach leaf curl and plum pocket can be controlled with a single fungicide application applied this fall after leaf drop or early next spring before bud swell.
 
Effective fungicides include Bordeaux mixture and chlorothalonil (Bravo, Daconil and others). Be sure to cover the entire tree including the bark and trunk. (Ward Upham)

Two of the common pesticides used in fruit tree sprays are malathion (for insects) and captan (for diseases). Unfortunately, both of these products are subject to alkaline hydrolysis. This is a process whereby certain pesticides will break down when mixed with high pH water. So let’s say you mix up your spray mixture by adding malathion and captan to 5 gallons of water. If that water has a pH of 7, the captan will break down so that only half of it will still be present in 8 hours.
 
However, if the water you use has a pH of 10, half the captan will break down in 2 minutes. Malathion isn’t nearly as sensitive but still will break down under high pH conditions though it is stable at a pH between 5 and 7. Note that alkaline hydrolysis does not affect all pesticides. Captan is the exception, not the rule. 
 
So, how do you bring down the pH of your spray water if it is high? Commercial people use buffering agents but that may be difficult for homeowners to find. Food grade citric acid can help. If you have a pH of 8.0, add 2 ounces of this citric acid per 100 gallons of water (1 and 1/4 teaspoons per 10 gallons) to bring the pH down to about 5.5. (Ward Upham)

Some parts of Kansas will have at least a partial peach crop that wasn’t killed by late frosts. To take advantage of this good fortune certain things should be done as the fruit matures to ensure a good harvest.
 
Control insects and diseases: Though it is too late to control peach leaf curl (see http://www.hfrr.ksu.edu/doc3168.ashx ), it is possible to control scab and brown rot.  Insects of concern are plum curculio, oriental fruit moth, plant bugs, and stink bugs. Use Captan or Immunox to control the diseases, and malathion to control the insects. Spray every 10 to 14 days. Pay attention to the waiting period between the last spray and harvest. See the publication, “Fruit Pest Control for Home Gardens” at http://www.ksre.ksu.edu/bookstore/pubs/c592.pdf   for details including organic controls.
 
Thin peaches: Thin peaches to 1 every 6 to 8 inches to maximize fruit size and to decrease the load on the branches. As a general rule, we need about 40 leaves per peach for maximum quality. Peaches are borne in clusters, so calculate how many a branch can support by dividing the length of the branch in inches by 7. As long as there is an average of 7 inches of branch length per peach, it doesn’t matter whether the peaches are in clusters or not.
 
Water Trees as Needed:   The most critical time for adequate water is during the pit hardening stage which usually lasts between 2 to 4 weeks. Cut open a few peaches to determine when the pit starts to harden or become woody. Irregular watering during this period can lead to split peaches.
 
Prop up branches if needed: Prop up branches if the fruit load is so heavy the tree may break apart. Use boards with a “V” cut in one end to support the branch. Prune the branch back to a smaller side branch next spring (March). (Ward Upham)

A common disease of roses is blackspot, a fungus disease that can cause defoliation of susceptible plants. Look for dark, circular lesions with feathery edges on the top surface of the leaves and raised purple spots on young canes. Infected leaves will often yellow between spots and eventually drop.

 The infection usually starts on the lower leaves and works its way up the plant.  Blackspot is most severe under conditions of high relative humidity (>85%), warm temperatures (75 to 85 degrees F) and six or more hours of leaf wetness. Newly expanding leaves are most vulnerable to infection. The fungus can survive on fallen leaves or canes and is disseminated primarily by splashing water.
 
Cultural practices are the first line of defense.
 
1. Don't plant susceptible roses unless you are willing to use fungicide sprays. For a list of blackspot resistant varieties, go to:  http://www.ppdl.purdue.edu/ppdl/weeklypics/3-22-04.html
 
2. Keep irrigation water off the foliage. Drip irrigation works well with roses.
 
3. Plant roses in sun in areas with good air movement to limit the amount of time the foliage is wet.
 
4. Remove diseased leaves that have fallen and prune out infected rose canes to minimize inoculum.
 
If needed, protect foliage with a regular spray program (10- to 14-day schedule) of effective fungicides. Recommended fungicides include tebuconazole (Bayer Disease Control for Roses, Flowers and Shrubs), myclobutanil (Immunox, Immunox Plus), triticonazole (Ortho Rose & Flower Disease Control) and chlorothalonil (Broad Spectrum Fungicide, Garden Disease Control, others). (Ward Upham)

Leaves Turning Yellow or Red: In Kansas we often see chlorosis (yellowing) of plant leaves due to high pH soils making iron unavailable.  However, there can other causes that result in similar symptoms. For example, we have received so much rain in certain parts of the state recently that plants are unable to take up the nutrients needed to maintain a good green color. The cause of this condition is actually a lack of oxygen in the soil due to soil pore space being filled with water.
 
This lack of oxygen to the roots often results in a yellowing of foliage. In certain plants such as oaks and maples, however, it may also lead to a reddening of some of the newer leaves. Fortunately, color changes due to wet soils will be corrected as soils dry. Plants should regain their color when we return to more normal weather.
 
Trees Shedding Leaves: If trees shed leaves in a general shedding with all parts of the tree losing some leaves, then there is no cause for concern. A general shedding of the leaves is most often due to weather turning hot and dry. The tree drops leaves because the root system can no longer keep up. Dropping leaves helps balance the amount of water available from the root system and the amount needed by the leaves.
 
However, the same thing can happen if the soil is too wet. A lack of oxygen in the soil compromises the root system so it can no longer support all the leaves. Therefore, the tree drops some leaves to bring the tree roots and leaves back into balance. The tree will retain more than enough leaves to remain healthy. (Ward Upham)

The frequent, heavy rains in certain areas of the state have resulted in the appearance of mushrooms in home lawns and landscape beds.  Although mushrooms are often spectacular in size and color, most are relatively harmless to plant life. Some of these mushrooms are associated with arc-like or circular patterns in turfgrass called fairy rings. The ring pattern is caused by the outward growth of fungal mycelium. The mycelium forms a dense, mat-like structure in the soil that decomposes organic matter. This decomposition releases nitrate into the soil, which in turn stimulates the growth of the grass at the outer portion of the ring. This results in a dark green appearance of the grass at the margin of the ring.
 
Unfortunately, the thick fungal mat formed by the fungus interferes with water infiltration. The fungus also may release certain byproducts that are toxic to the turf. This can lead to dieback of the turf close to the ring. Fairy rings are difficult to control. You can sometimes eliminate the ring by digging to a depth of 6 to 12 inches and 12 inches wide on both sides of the ring, refilling the hole with non-infested soil. Or you can try to mask the symptoms by fertilizing the rest of the lawn so that it is as dark green as the ring. This often isn't a good idea because it tends to promote other turf problems. Commercial people can use certain fungicides to control fairy rings but these products are not available to homeowners. See http://www.ksre.ksu.edu/bookstore/pubs/EP155.pdf  for more info on these fungicides.
 
Some mushrooms in lawns are not associated with fairy rings. These may be mycorrhizal (symbiotic association with tree roots) or saprophytic (live on dead organic matter such as wood, etc.) in the soil. Because some of these mushrooms are beneficial, you don't really want to kill them. Besides, a fungicide spray to the mushroom itself does little good. Remember the mushroom is simply the fruiting structure of the organism. Most of the fungus is below ground and inaccessible to the chemical. If mushrooms are a nuisance, pick them and dispose of them as soon as they appear. Remove sources of large organic debris from the soil. Also, mushrooms tend to go away as soil dries. Patience may be the best control. Some of the mushrooms in the lawn are edible, but others are poisonous. Never eat mushrooms unless you are sure of their identity. (Ward Upham)

Aphids are small insects, about an eighth of an inch long. They are soft-bodied, pear-shaped and of many colors, such as green, black, gray, yellow or red. Some are winged during certain times of the year.
 
Aphids feed by sucking sap from buds, leaves, twigs and developing fruit. Most of that sap is passed through their body and ejected through two small “pipes” known as cornicles that project from the rear of their bodies. This ejected, sticky
material is called honeydew. This honeydew often becomes black with sooty mold fungus. Automobiles parked under trees with large aphid populations will often be spotted with honeydew. Though the finish will not be harmed by the honeydew, it is a hassle to clean off.
 
Aphids usually are controlled effectively by nature. Adverse weather conditions such as beating rains and low temperatures, as well as fungus diseases, insect predators and parasites, keep the aphids in check. Aphid enemies include lady beetles, syrphid fly larvae, aphis lions and small wasp parasites known as braconids.
 
Most insecticide applications destroy beneficial insects as well as pests and leave trees or shrubs unprotected if pest resurgence occurs. Because beneficial insects play an important role in natural aphid control, try washing aphids away with a forceful stream of water (if practical) before using insecticide sprays.
 
If control measures are warranted, use insecticidal soaps, horticultural oils, malathion, cyfluthrin or permethrin. Reapplication may be needed. Imidacloprid (Annual Tree and Shrub Insect Control, 12 Month Tree & Shrub Insect Control, Max Tree and Shrub Insect Control, Bonide Systemic Granules IC, Bayer Tree and Shrub Insect Control) is a systemic insecticide that can be used to prevent aphid populations from building but must by applied early to allow time for the pesticide to move to the new growth. This time period may vary from one week to three months depending on the size of the plant with very large trees taking the most time. (Ward Upham)

We had a report last week from the Wichita area that a number of ash trees have ash sawfly larvae feeding on the leaves.
 
These sawfly larvae are a light green color with a broad, whitish stripe on the top side.  In the middle of the whitish stripe there appears to be a darker green stripe that is actually the digestive tract of the insect.  Though sawfly larvae resemble caterpillars, they have at least six pairs of "stublike" prolegs behind the three pairs of true legs on their abdomen. (Caterpillars never have more than five pairs of prolegs.)
 
There are usually no detrimental effects to the health of the tree if nature is allowed to run its course. Even if all the leaves are eaten, it is early enough in the growing season for trees to put out a complete new set of leaves and still has enough time to make all the food reserves needed to survive the coming winter. However, if control is desired, a number of insecticides can be used for control including cyfluthrin (Bayer Lawn and Garden Multi-Insect Killer), malathion, esfenvalerate (Monterey Bug Buster II) and carbaryl (Sevin). An effective organic product is spinosad (Captain Jack’s Deadbug Brew; Fertilome Borer, Bagworm, Leafminer and Tent Caterpillar Spray; Monterey Garden Insect Spray). Horticultural oils and insecticidal soaps are also effective because of the soft skin of sawfly larvae. (Ward Upham)
 
Contributors:  Ward Upham, Extension Associate