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Horticulture Newsletter 2016, No. 38

9/20/2016

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Video of the Week:
Protecting Fruit Trees from Deer

Flowers:
Time to Plant Spring-flowering Bulbs

Picture
Late September through October is an excellent time to plant spring-flowering bulbs such as crocus, tulips, and daffodils. These plants need to develop roots in the fall and must meet a chilling requirement over the winter in order to bloom in the spring.
 
Choose a planting site that has full sun to partial shade. The ideal soil would be a sandy loam, but even poor soils can be used if organic material such as peat moss, compost, or aged bark is mixed in. For example, a heavy clay can be amended by mixing in one-third to one-half organic material. Soil pH should be between 6.0 and 7.0.
 
Bulbs need good aeration as well as good drainage for proper development. It is best if the bulbs are given 12 inches of prepared soil. If one-third organic material were added, this would require mixing 4 inches of organic material with 8 inches of soil. Incorporate about 3 pounds of a complete fertilizer such as a 5-10-5 per 100 square feet during preparation or fertilize according to soil test.
 
Planting depths vary depending on the size of the bulbs. For example, tulips and hyacinths are set about 6 inches deep, and daffodils are put 6 to 8 inches deep. Smaller bulbs are planted shallower. As a rule of thumb, bulbs are planted two to three times as deep as their width. Planting depth is the distance from the bottom of the bulb to the top of the soil. Large bulbs are normally spaced 4 to 6 inches apart, and small bulbs about 1 to 2 inches. Planting in clumps or irregular masses produces a better display than planting singly.
 
After placing the bulbs at the proper depth, replace half the soil and add water. This will settle the soil around the bulbs and provide good bulb/soil contact. Add the remaining soil and water again. Although there will be no top growth in the fall, the roots are developing, so soil needs to be kept moist but not soggy. Mulch can be added after the soil has frozen to prevent small bulbs from being heaved out of the soil by alternate freezing and thawing. (Ward Upham)

Vegetables:
Rotation of Vegetable Crops

Picture
Rotating vegetable crops is a standard way of helping prevent disease from being carried over from one year to the next. Rotation means that crops are moved to different areas of the garden each year. Planting the same crop, or a related crop, in the same area each year can lead to a build-up of disease. Also, different crops vary in the depth and density of the root system as well as extract different levels of nutrients. As a rule, cool-season crops such as cabbage, peas, lettuce and onions have relatively sparse, shallow root systems and warm-season crops such as tomatoes, peppers and melons have deeper, better developed root systems. Therefore, it can be helpful to rotate warm-season and cool-season crops.
 
As mentioned earlier, it is also a good idea to avoid planting closely related crops in the same area as diseases may be shared among them. For example, tomatoes, potatoes, peppers and eggplant are closely related. Also, broccoli, cauliflower, cabbage and brussels sprouts share many characteristics in common. Therefore, do not plant cabbage where broccoli was the previous year or tomatoes where the peppers were.
 
So, why is this important to bring this up in the fall?  Now is the time to make a sketch of your garden so that the layout is not forgotten when it is time to plant next year. (Ward Upham)

Ornamentals:
Planting Trees in the Fall

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The fall season can be an excellent time to plant trees. During the spring, soils are cold and may be so wet that low oxygen levels inhibit root growth. The warm and moist soils associated with fall encourage root growth. Fall root growth means the tree becomes established well before a spring-planted tree and is better able to withstand summer stresses. However, certain trees do not produce significant root growth during the fall and are better planted in the spring. These include beech, birch, redbud, magnolia, tulip poplar, willow oak, scarlet oak, black oak, willows, and dogwood.
 
Fall-planted trees require some special care. Remember, that roots are actively growing even though the top is dormant. Make sure the soil stays moist but not soggy. This may require watering not only in the fall but also during the winter months if we experience warm spells that dry the soil. Mulch also is helpful because it minimizes moisture loss and slows the cooling of the soil so root growth continues as long as possible. Evergreens should be moved earlier in the fall than deciduous plants. They need at least six weeks before the ground freezes for the roots to become established. (Ward Upham)

Miscellaneous:
Adding Organic Materials Directly to the Garden

Picture
If the summer weather has brought an early end to your garden, consider adding organic materials directly to the soil rather than composting. Materials such as residue from lawn renovation, rotted hay, or rotted silage can be added and then tilled in. Coarser materials such as tree leaves or garden residue should be shredded. A lawn mower with a bagging attachment can be used to shred this material and collect it in one operation.
 
Organic materials can be spread to a depth of about 3 inches and tilled in. Be sure the soil is not too wet before tilling. During warm weather, the material will decompose quickly and the process can be repeated every two weeks. Later in the fall, it may take longer. This process can be repeated from now until late November to early December.
 
Remember that organic matter helps almost any soil. It improves clay soil by improving tilth, aeration and how quickly the soil takes up water. In sandy soils, it acts as a sponge by holding water and nutrients. (Ward Upham)

Moving Houseplants Inside for the Winter

Picture
Many people with houseplants move some of them outside for the summer to give them better growing conditions and help them recover from the stress of an indoor environment. But as fall approaches and night temperatures approach 50 F, it is time to think about bringing plants inside for the winter. Plants that have spent the summer outside should be inspected for insects and disease before bringing them inside. A sharp spray from a garden hose can remove insects or mites from houseplant foliage. Insects in the potting soil can be forced out by soaking the pot in a tub of lukewarm water for about 15 minutes.
 
Houseplants that have been kept outdoors are accustomed to receiving much more sunlight than they do indoors. So how do we help houseplants acclimatize to the lower light levels inside? Houseplants brought in from outside should be started out in an area of the home that receives plenty of light, and then gradually moved to their permanent, darker location. This process should take four to eight weeks depending on the degree of difference in light levels between the initial and final location of the plant.
 
Understanding plant processes allows us to anticipate potential problems. Acclimatization gives houseplants a greater chance of retaining leaves and avoiding the stress of completely replacing them. (Ward Upham)

Pests:
Itch Mites are Back

Picture
Last year was a bad year for itch mites. It looks like 2016 may be bad as well.  These arthropods are responsible for painful bites that result in itching on people. The mites are barely visible to the naked eye but their bite results in a noticeable raised red area with a centralized blister. It normally takes 10 to 16 hours for itching to start after exposure. Unlike chigger bites which are usually restricted to areas where clothing is tight such as belts, underwear or socks, oak leaf itch mite bites appear where clothing is loose such as at the neck, shoulder and chest.
 
Oak leaf itch mites feed on insect larvae living within straw, seeds and plant galls.  In recent outbreaks, itch mites have been feeding on midge larvae which cause gall formation on the margins of certain oak leaves.  Pin oaks are most likely affected but red oaks and black oaks can also act as a host for the midges. The female mite is able to enter the gall through small openings and paralyze the midge larvae with a neurotoxin.  The midge then acts as a food source for the mite allowing her to develop about 200 offspring. It takes about a week for the new mites to emerge. Only about 5 to 10 percent of the progeny are males. The males do not feed but mate and then die.  Females seek new hosts on the existing tree but can be carried by winds for hundred of yards. Mite populations appear in late July and continue through the summer and into the fall.
 
No effective control has been found. Deet-based repellents have not given consistent results. Tree sprays are ineffective as the mites are protected by the galls.  Oak trees known to be infested with mites should be avoided. If work must be done near oak trees with marginal leaf gall, bathing and changing and washing clothing is recommended. This article was adapted from our publication MF2806, “Oak Leaf Itch Mite.” (Ward Upham)
 
Contributors: Ward Upham, Extension Associate

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Horticulture Newsletter 2016, No. 19

5/10/2016

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Video of the Week:
Cantaloupe: Varieties for Small Spaces

Upcoming Events:
Garden Tour in Kansas City Area

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

Vegetables:
'Staggering' Sweet Corn Planting

sweet corn planting
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)

Fruit:
Thinning Excess Fruit

apples on tree
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)

Pests:
Cabbage Worms

cabbage worm
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)

Bristly Rose Slug

bristly rose slug
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)

Ladybird Beetles

ladybird beetle larvae
​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)

Ornamentals:
Vein Pocket Galls on Oak

vein pocket gall on oak leaf
marginal pocket gall on oak leaf
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)

Miscellaneous:
Moving Houseplants Outside for the Summer

houseplant outside
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 the Garden

rabbit
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

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Horticulture Newsletter 2015, No. 40

10/6/2015

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Video of the Week:
Overwintering Geraniums

Upcoming Events:

​Kansas Turfgrass Conference in conjunction with Kansas Nursery & Landscape Association
December 1, 2 & 3, 2015
Kansas Expocentre, Topeka
For more information, go to  http://www.kansasturfgrassfoundation.com/
 
Great Plains Growers Conference
January 7, 8 & 9, 2016
St. Joseph, MO
 
RetailWorks
February 4, 2016
Manhattan, KS

Vegetables:
Last Tomatoes of the Season

Mature green stage tomato
​Cold nights are increasing in frequency now that we are into October. If you have tomatoes, you may have some that are approaching maturity.  Leave them on the vine until mature or until a frost is forecast. Tomatoes will ripen off the vine but must have reached a certain phase of maturity called the ‘mature green stage.’ Look for full-sized tomatoes with a white, star-shaped zone on the bottom end of the green fruit.
        
When harvesting fruit before a frost, separate tomatoes into three groups for storage: those that are mostly red, those that are just starting to turn, and those that are still green. Discard tomatoes with defects such as rots or breaks in the skin.  Place the tomatoes on cardboard trays or cartons but use layers of newspaper to separate fruit if stacked. Occasionally a tomato may start to rot and leak juice. The newspaper will keep the juice from contacting nearby or underlying fruit. Store groups of tomatoes at as close to 55 degrees as possible until needed. (Ward Upham)

Peppers from the Garden

Picture
​Peppers are able to be stored fresh much longer than tomatoes. They can usually keep in a crisper drawer of a refrigerator for several weeks if kept moist but not wet. For longer storage, freezing works well. Though mushy when thawed, the flavor still comes through in cooked foods. Try dicing them into small pieces and then freezing on a cookie sheet. The frozen pieces can then be poured into a plastic bag for later use.  Measuring is much easier as the pieces are not frozen together in a clump. This methods works equally well for hot peppers. (Ward Upham)

Fall Planting of Asparagus and Rhubarb

Picture
​We sometimes receive questions as to whether asparagus or rhubarb can be moved in the fall. Though these crops are traditionally transplanted in the spring (mid-March to mid-April), a fall move can be successful. Wait until the top has been browned by frost and then cut back to the ground. 
        
Prepare the soil and fertilize as you would in the spring. See http://www.bookstore.ksre.ksu.edu/pubs/mf319.pdf  for more detail on asparagus and http://www.bookstore.ksre.ksu.edu/pubs/ep99.pdf  for more information on rhubarb.
        
Water well after planting to insure good root/soil contact. Mulching would be helpful on the rhubarb to prevent the plant from heaving out of the soil during the winter but asparagus requires no such treatment as it is planted much deeper. (Ward Upham)

Turfgrass:
Frost on Lawns

Picture
​If you have ever walked across a frosted lawn that isn't dormant, you may have noticed your footprints showing up later in the day. Though this is unsightly, it does not kill the turf. Grass blades are damaged but the crown is not. Actively growing turf will often recover after two to four mowings. Damage that occurs this late in the fall will continue to show damage until it is masked by the rest of the lawn turning brown due to cold weather. It is believed that the damage is caused by ice crystals killing plant cells when they are forced into the leaf by the weight of a wheel or foot. Remember to avoid damage by staying off of frosted turf. (Ward Upham)

Should You let Turf Grow Tall in the Fall

Picture
​Sometimes you will hear people say to let the grass grow tall right before winter sets in. Their reasoning is that the extra foliage will insulate the crown of the plant from the extreme cold of winter. Although this may sound reasonable, in practice it probably does little, if anything, to increase winter hardiness. On the contrary, a canopy that is too high during the winter may lay over and become matted down, leading to an increased incidence of winter-diseases such as snow mold.
        
Turfgrass species vary genetically in their cold tolerance, with warm-season grasses being less cold tolerant than the cool-season types. Given these differences, cold tolerance is improved by increasing the health of the plants going into the winter, and healthy plants are a result of a sound management program (fertilizing, watering and mowing) during the spring, summer and fall. The lawn will benefit more from continuing to mow at the recommended height than from trying to gain some insulation against winter cold by allowing it to grow tall.
        
Here is a list of the recommended mowing height ranges (in inches) for home lawns in Kansas:
         Tall fescue 2.5 -3.5
         Kentucky bluegrass 2-3
         Perennial ryegrass 2-3
         Buffalograss 2-3
         Bermudagrass 1-2
         Zoysiagrass 1-2
 
(Note: Mowing at heights below 1.5 inches requires a reel mower). There may be some benefits  gained by adjusting mowing heights WITHIN the recommended range at times. For example, it is a good practice to mow warm-season grasses at the higher end of recommended heights during late summer and early fall because this practice should help them store more carbohydrate reserves for the winter, and it may reduce the incidence of certain cool-weather diseases. But the rule to remember is to stay within the recommended height range for your species. (Ward Upham)

Ornamentals:
Fall Colors of Trees

Picture
​Part of the allure of fall foliage is color variation. There are trees that turn red, purple, yellow, orange and brown.
        
Specific plant pigments determine individual colors. Foliage derives its normal green color from chlorophyll, the substance that captures the energy of the sun. Other pigments produce fall colors. Reds and purples are caused by anthocyanins, yellows by xanthophylls, and oranges by a combination of carotenes and xanthophylls. Browns are the result of tannins present in the leaf. Most of these substances are present throughout the growing season but are masked by the green color produced by chlorophyll. Anthocyanins are the exception and are produced after the chlorophyll is destroyed in the fall.
        
If you have ever seen pictures of New England in the fall, you have probably wondered why trees in Kansas usually do not color as well. This difference is partly because of the tree species prevalent in New England. Certain oaks and maples naturally produce good color. Coloring also is influenced by the weather.
        
Warm, sunny days and cool nights are ideal for good color. The sunny days encourage photosynthesis and, thus, sugar accumulation in the leaves. As fall progresses, each leaf develops an abscission layer at the base of the petiole, or leaf stem, that prevents these sugars from being transported down the trunk to the roots for storage. This high sugar content in the leaves produces more intense colors. Cloudy days and warm nights prevent some of the sugar accumulation in the leaves and results in less vibrant colors.
        
Weather during other parts of the growing season also can have an effect. Heavy rains in the early spring or hot, dry weather during the summer can both have a deleterious effect on fall color.
        
The length of time a tree maintains fall color also depends on weather. Reds, yellows and oranges are short-lived when trees undergo frosts and freezes. (Ward Upham)

Pests:
Oak Leaf Itch Mite

Picture
​Whereas scratching an itch sometimes provides satisfying (almost pleasurable) relief, at other times scratching an itch can be painful and distressing. The latter situation is attributable to the mite, Pyemotes herfsi (Oudeman).
        
Unlike chiggers which have been long-recognized for producing annoying but fleeting bouts of itchiness, mysterious “bites” causing raised quarter-sized reddened areas each with a centralized pinhead-size blister were of widespread occurrence in 2004 in various Midwestern states.
           
Through investigative studies, the Pyemotes herfsi mites were identified as being responsible for the mysterious bites. Although the existence of these mites had been well known for multiple decades, the correlation between them and reported widespread occurrences of human discomfort was unknown. The severity of the 2004 outbreaks resulted in cooperative efforts between K-State and the University of Nebraska entomologists, the resultant being the identification of Pyemotes herfsi as responsible for the stressful skin disorders.
           
Pyemotes herfsi were recovered from marginal fold galls on (primarily) pin oak leaves. Marginal galls are associated with the larvae/maggots of tiny midges. That is, Pyemotes herfsi prey upon the midge larvae. The following side-by-side close-up images show an intact marginal gall, and a dissected gall revealing female Pyemotes herfsi. Despite their small size, they become readily visible due to their bulbous abdomens which can contain up to 200 offspring.
           
Due to their minuscule size compared to that of midge larvae, Pyemotes herfsi possess a potent neurotoxin used to paralyze their maggot hosts. This toxin is that which is responsible for initiating the skin irritations which cause discomfort in individuals upon which Pyemotes herfsi happens to come in contact with. Because Pyemotes herfsi are associated with the midge larvae responsible for marginal galls on oak leaves, Pyemotes herfsi have been given the common name, Oak Leaf Itch Mite. It is believed that oak leaf itch mites also prey upon the larvae of another closely related midge species responsible for the formation of vein pocket galls on the undersides of oak leaves. A full description of the oak leaf itch mite life cycle is available online by accessing Kansas State University Extension Publication MF2806.
           
The good news is that oak leaf itch mite populations may be extremely low or absent for years-on-end ------ people can enjoy the outdoors without having to contend with oak leaf itch mite encounters. The bad news is that the reappearance/resurgence of oak leaf itch mite populations is unpredictable.
           
More bad news: Each female oak leaf itch mite produces many progeny. And the developmental cycle is reported to be just 7 days. The resultant is the production of uncountable numbers of oak leaf itch mites which ultimately leave the confines of leaf galls. Passive dispersal via air currents is the bane to people, especially those in neighborhoods where pin oaks constitute the main trees species.
           
The bad news continues: There is a wide time frame during which encounters with oak leaf itch mite might occur. It is not only the initial late summer encounters, but the presence of oak leaf itch mites extending well into the fall when people are raking leaves and kids having fun playing in leaf piles.  And if this is not enough negativity regarding oak leaf itch mites, there is little to be done (well, actually nothing to be done) in treating and reducing/eliminating their populations.
           
The people who are most likely to encounter oak leaf itch mites will be those in living in areas/neighborhoods where oaks (again, especially pin oaks) are the dominant tree species. When oak leaf itch mite populations are excessive, restricting outdoor activities is one method of reducing the risk of exposure. While the use of repellents may work against annoying insect species which actively seek a host, repellents have little effect against oak leaf itch mites which are passively dispersed, and lack the ability to alter their course/direction. It has been suggested that susceptible individuals (yes, some people do not have negative reactions to oak leaf itch mite bites) spend as little outdoor time as possible. And showers immediately upon returning indoors might eliminate/wash off mites before they bite and cause reactions.
           
Individuals experiencing oak leaf itch mite encounters might utilize medications and lotions so designed to provide relief from itching discomfort as well as secondary infections of excoriated areas. Seek advice and recommendations from appropriate personnel. (Bob Bauernfeind)
 
Contributors: Bob Bauernfeind, Entomology; Ward Upham, Extension Associate

​Kansas Turfgrass Conference in conjunction with Kansas Nursery & Landscape Association
December 1, 2 & 3, 2015
Kansas Expocentre, Topeka
For more information, go to  http://www.kansasturfgrassfoundation.com/
 
Great Plains Growers Conference
January 7, 8 & 9, 2016
St. Joseph, MO
 
RetailWorks
February 4, 2016
Manhattan, KS
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    Authors

    Ward Upham runs the Horticulture Response Center in the Department of Horticulture and Natural Resources at Kansas State University. Other contributors include K-State Extension Specialists.

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