​If you have vegetables that are blooming but not setting fruit, you may have a problem with flower pollination. There are several possible reasons for this that usually vary by species. One condition that can affect several species at the same time is overfertilization. Too much nitrogen causes the plant to emphasize vegetative growth, often to the detriment of fruit production.  Overfertilization can lead to a delay in flower production and a decrease in fruit set among the flowers produced.

Squash, cucumbers, watermelon, and muskmelon can have a couple of other problems. First, the early flowers on these plants are usually all male. The production of both male and female flowers becomes more balanced as time passes. You can easily tell the difference between the two because only the female flower has a tiny fruit behind the blossom. If you have both, have not over-fertilized, and still have a problem, make sure you have pollinators. 

Look for the presence of bees visiting the plants. If you don't see any, try hand-pollinating several flowers.  Use a painter’s brush to transfer pollen from the anther of the male flower to the stigma of the female flower. If you get fruit on only those flowers you pollinated, you need more pollinators.  Make sure you aren't killing them with overuse of insecticides.  If you must use an insecticide, spray near dusk when the flowers have closed. 

Tomatoes are wind pollinated and therefore not dependent on pollinators. But they have another possible problem which is temperature. Tomatoes normally won't set if the night temperature is below 50 due to sparse pollen production. They also won't set when nighttime temperatures are above 75 degrees F and daytime temperatures are above 95 degrees F with dry, hot winds.  Under such conditions, fertilization is not completed and no fruit develops.  (Ward Upham)

August 4         Kansas Turfgrass Field Day, Manhattan
 https://turffieldday.eventbrite.com
 The field day program is designed for all segments of the turf industry - lawn care, athletic fields, golf courses, and grounds maintenance. Included on the program are research presentations, problem diagnosis, commercial exhibitors, and equipment displays. There will be time to see current research, talk to the experts and get answers to your questions. Pesticide recertification credit in 3B is available and 0.25 GCSAA education points
 
August 15       K-State Vegetable Research Field Day, Olathe
http://hnr.k-state.edu/events/2016%20GG%20Vegetable%20Research%20Tour.pdf

Apples mature over a long period of time depending on variety. Some varieties such as Lodi can mature in July and others as late as October.  Here are some guides to help you decide when to pick your apples.
 
Color change: As apples mature, the skin color in areas of the stem and the calyx basin at the bottom of the apple turns from an immature green to a light-yellow color. Some apples will develop a red skin color before they are ripe, so this is not a reliable indication of maturity.
 
Flavor: This is a good guide if you are familiar with the apples you have and know how they should taste. Even if you do not know the characteristic flavor of the kind of apple you have, you can still sample slices of a few apples and decide if they have a sweet flavor. If they are not ready to harvest, they will taste starchy or immature. If apples have already fallen and taste a bit starchy, store them for a period to see if they become sweeter.
 
Flesh color: As apples mature and starches change to sugars, the flesh changes from very light green to white. When you cut a thin slice and hold it up to the light you can see the difference.
 
Days from bloom: The number of days from bloom is a reliable guide for general maturity time, but weather conditions will have some influence. Some kinds of apples and approximate days from bloom to maturity are Jonathan, 135, Delicious, 145, Golden Delicious, 145, and Winesap,155 days. This process may be slower than usual due to the cooler weather this year.
 
Seed color: The seeds of most apples change from light green to brown as the fruit ripens. This indicator should be combined with other changes since it is not absolute. The flavor of the apples, the change in color of the stem and calyx basins and flesh color are important in deciding if apples are ready to harvest. (Ward Upham)

As fruit growers are harvesting peaches, some are noticing split pits and/or pitburn.
 
Pitburn is evidenced by brown or gray areas around the pit and is caused by high temperatures and rapid growth. It actually isn’t the high temperatures that injure the flesh directly but a lack of oxygen interfering with normal development.  Remember the very high temperatures we had earlier in the year?  Those high temperatures led to pit burning.
 
Split pits are also often the result of rapid growth and can be made worse with excessive thinning and/or irregular watering during the pit hardening stage. Such peaches are more likely to rot than those with intact pits.
 
There isn’t anything that can be done at this stage to help the peaches.  However, a good job of watering and avoiding overthinning can help prevent split pits in the future. Peaches with pitburn or split pits are safe to eat.  (Ward Upham)

This is the time of year we normally think of planting a fall garden. Crops that can be planted now include lettuce, radishes, spinach, and similar crops. There still is time to raise another crop of green beans along with some summer squash. If you can find plants, cabbage, broccoli and cauliflower can also mature during the fall season.

Planting a fall garden is just like planting a spring garden with some big advantages. You will find the weed pressure to be much less and insect problems may be far fewer than in a spring garden. Seeds will germinate rapidly, so you will have crops up and growing in just a few days – compared to several weeks in the spring.
 
There are a few drawbacks to fall gardening, and one of those is that you must provide regular, frequent watering (possibly daily) until the crops are up and growing. It is best to plant seeds deeper than you do for a spring garden because soil is cooler and moister down a little deeper.
 
As far as soil preparation is concerned, don't get too excited about deep tillage for a fall garden. Lightly work the soil enough to establish a seedbed; reserve your deep tillage for later in the fall. Also, don't concentrate on adding a lot of organic matter and fertilizer for the fall garden. The organic matter can be added later in the fall with the deeper tillage, and excessive fertilizer application in hot weather is not a good idea. If you have some crop residue to remove from a previous crop, chop the residue with a lawn mower and lightly till the soil surface after the residue has had a chance to dry for 2 to 3 days. (Ward Upham)

Chiggers are mites, not insects. And like all mites, the adults have eight legs. However, the larva only has six legs. Though the bright red female adult is tiny (about 1/20th of an inch) the larva is much smaller (about 1/150th of an inch). Only the larvae are parasitic and attack animals. The larva injects digestive juices into the skin, which causes a rapid swelling. In the center of the swelling is a "feeding tube" from which the chigger sucks out liquefied skin cells. Feeding usually continues for 2 to 4 days.
 
Protection from chiggers uses two approaches. The use of a repellent can discourage chiggers from attacking. The most effective repellents are Deet and permethrin. Both are applied to clothing. The second approach seeks to reduce chigger populations. Keeping the lawn mowed regularly can help, but large populations may require the use of an acaricide. Effective products include bifenthrin (Talstar, Hi-Yield Bug Blaster II, Hi-Yield Bug Blaster Bifenthrin, and Ortho Lawn Insect Killer Granules), cyfluthrin (Tempo 20, Bayer Vegetable & Garden Insect Spray) and carbaryl (Sevin). For more information, see the K- State Research and Extension publication titled, “Chiggers” at:  http://www.ksre.ksu.edu/bookstore/pubs/MF2107.PDF  (Ward Upham)

A number of people have asked the name of the weed with the large leaves and purple-black berries that hang in a cluster. This perennial is known as pokeweed. All parts of this plant are poisonous, especially the roots. Signs of poisoning include abdominal cramps, diarrhea, vomiting, weakness, drowsiness and difficulty in breathing. One of the toxins found in pokeweed is the protein lectin, which can cause abnormalities in white blood cells.
 
Surprisingly, young leafy springtime shoots are sometimes eaten after thorough cooking. Though cooking eliminates most of the toxins, there is still a danger of being poisoned from handling and preparing the shoots as well as ingesting improperly cooked plants.
 
Berries can be attractive to children. Cut down and discard pokeweed that might come into contact with kids. This plant is a perennial. You may want to spray it with a herbicide next year before it is large enough to be attractive to children. (Ward Upham)

​We sometimes receive complaints from homeowners regarding the lack of effectiveness of various pesticides. There can be a number of reasons for this lack of efficacy. Here are some of the common ones:
 
1. Lack of good foliage penetration. This often is a problem when spraying for bagworms on junipers.  The spray must penetrate the foliage and reach the bagworms toward the inside of the plant. High-pressure commercial sprayers are able to get the spray to the insects but homeowner models are much more problematic. With pump-up sprayers, you may have to push the wand through the outer layer of foliage to reach insects toward the inside of the plant.
 
2. Not spraying where the insect is. Many of our insects and mites feed on the underside of leaves. If the plants are sprayed over the top, little to no pesticide reaches the pests. This problem is often seen with spider mites on broadleaf plants and cabbage worms on cabbage, broccoli and cauliflower.
 
3. Maturity of pest. Insects become much more difficult to control when they become adults. For example, Sevin does a good job of controlling young, early instar grasshoppers but is much less effective on adults.
 
4. Level of disease pressure. Most fungicides are better used as preventatives than as curatives. If a disease gets firmly established, it may be difficult to bring it back under control. For example, chlorothalonil is effective in controlling early blight and Septoria leaf spot on tomato if used as a preventative. However, chlorothalonil will not control these diseases on badly infested plants.
 
5. Choosing the wrong product. Homeowners often use a product they have on hand. However, products differ markedly in how well they control specific pests. Make sure the pest you wish to control is on the label. Unfortunately, even labeled products may vary in effectiveness. Check K-State Research and Extension recommendations for products.
 
6. Using the wrong rate. Using less than recommended rate can reduce effectiveness but using more can also cause problems.  For example, using a systemic herbicide such as Roundup at higher than recommended rates can burn off the top of the plant before the herbicide is translocated to the roots, thereby reducing effectiveness.
 
6. High pH spray water. Certain pesticides are not stable in high or low pH water. Following are  some examples.

* Captan has a half-life of 3 hours at a pH of 7.0, but only 10 minutes at a pH of 8.0.
* Carbaryl (Sevin) has a half-life of 24 days at pH 7.0, but only 1 day at pH 9.
 
The half-life of a product is the amount of time it takes for half of the product to be neutralized. For example, if you apply 3 ounces of a product to a gallon of water and the half-life is 8 hours, only half of the product is still active at 8 hours, one-fourth of the product is active 16 hours and 1/8 of the product is still active at 24 hours. (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

Some gardeners would like to harvest apples early. Though nearly mature apples can ripen off the tree, there must be a certain level of maturity for this to happen. Here are some guides to help you decide when to pick your apples.

Color change: As apples mature, the skin color in areas of the stem and the calyx basin at the bottom of the apple turns from an immature green to a light-yellow color. Some apples will develop a red skin color before they are ripe, so this is not a reliable indication of maturity.

Flavor: This is a good guide if you are familiar with the apples you have and know how they should taste. Even if you do not know the characteristic flavor of the kind of apple you have, you can still sample slices of a few apples and decide if they have a sweet flavor. If they are not ready to harvest, they will taste starchy or immature. If apples have already fallen and taste a bit starchy, store them for a period to see if they become sweeter.

Flesh color: As apples mature and starches change to sugars, the flesh changes from very light green to white. When you cut a thin slice and hold it up to the light you can see the difference. 

Days from bloom: The number of days from bloom is a reliable guide for general maturity time, but weather conditions will have some influence. Some kinds of apples and approximate days from bloom to maturity are Jonathan, 135, Delicious, 145, Golden Delicious, 145, and Winesap, 155 days. This process may be slower than usual due to the cooler weather this year.

Seed color: The seeds of most apples change from light green to brown as the fruit ripens. This indicator should be combined with other changes since it is not absolute. The flavor of the apples, the change in color of the stem and calyx basins and flesh color are important in deciding if apples are ready to harvest. (Ward Upham)

Plant salad crops such as lettuce, radishes, spinach, turnips, mustard and other greens from mid-August to early September for a fall harvest.  Plant slightly deeper than you did in the spring.  This will keep the seed slightly cooler though still warm and the soil should retain moisture longer.  Water frequently (if needed) until seedlings start to emerge — which should be fast with our warmer soils.  Watering heavy soils can sometimes cause a crust to form.  This can be prevented by a light sprinkling of peat moss, vermiculite or compost directly over the row. Reduce watering frequency after plants emerge.  Plants may need to be protected from hungry rabbits and insects. (Ward Upham)

Lilac borers are insects whose larvae bore into stems usually during May and June. A sawdust-like material call frass is often seen around the base of stems after it has been pushed out the hole made by the borer. Canes often wilt and die during late summer especially if the summer has been dry. The larvae passes the winter inside the dead canes and pupates the following spring, usually during April. The adult, clear-winged moth resembles a wasp and often emerges during May through June though there is a great deal of variability. Eggs are laid on the stems of lilac, and the cycle starts over again. There is one generation in Kansas.

Though it is too late to spray for lilac borer this year, removal and destruction of dead canes will help reduce populations next year. You may also want to spray for the insect next spring. The first spray for ash/lilac borer should be applied when the Vanhoutte spirea is in full to late bloom, probably by about May 1.  A second spray should be applied four weeks after the first.  Thoroughly treat the lower portion of the stem of lilac or privet. Permethrin (Hi-Yield 38 Plus and Hi-Yield Garden, Pet, and Livestock Insect Control) are labeled for control. Though there are a number of other homeowner products that contain permethrin, the products listed above are the only ones I've found that specify how the material should be applied for borer control on the label. (Ward Upham)

We are seeing a number of tree and shrub species, including pyracantha and English oak, with browning or bronzing leaves due to lacebug damage. Woody plants that I have seen affected this year include oaks, hawthorns, cotoneaster and sycamore. Lacebugs are very small insects with wings that resemble lace under magnification. All stages of the insect develop on the undersides of leaves where they suck the sap. Adults are about 1/8-inch long. Under heavy infestations, stippling damage becomes evident. The leaves lose their green color, becoming pale and the undersides of the leaves may become speckled with brownish-black excrement spots and cast nymphal skins.

Healthy trees will not be damaged by lacebug this late in the season. The trees had plenty of time during the spring and summer to make the food needed to survive the winter. Control measures are not recommended. (Ward Upham)

There are normally two generations of this insect in Kansas with this being the second generation. All species of elms are attacked, but Siberian elms (often referred to as Chinese elms) are preferred.

Elm leaf beetles are serious nuisance pests of elms. Both adults and larvae feed on the elm leaves. Adult beetles are green-and-yellow striped and about 1/3-inch long. Young larvae are black and hairy but become yellow with two longitudinal dark stripes as they mature. The larvae cause most of the injury by window-feeding on foliage, resulting in a skeletonized appearance.  Heavily infested leaves turn brown as if scorched by fire and often will drop prematurely. After several weeks of feeding, the larva crawl down the trunk or fall to the ground where they pupate.  Elm leaf beetles overwinter as adults.

Active larvae can be controlled with a number of insecticides. However, check to make sure that larvae are still active before spraying. In many cases, the larvae have dropped from the trees and are pupating. Spraying is ineffective and unnecessary once pupation starts. Effective sprays for larvae (and adults) include carbaryl (Sevin), acephate (Acephate, Orthene), spinosad (Conserve; Captain Jack’s Dead Bug Brew, Borer; Bagworm, Leafminer & Tent Caterpillar Spray) lambda-cyhalothrin (Scimitar, Spectracide Triazicide, Bonide Beetle Killer). (Ward Upham)

Contributors: Ward Upham, Extension Associate