June 28, 2004

ENTOMOLOGY

Codling moth hatch of first generation eggs was completed early last week, based on degree day (DD) accumulations since biofix at the WVU KTFREC.  Hatch of second generation eggs is expected to begin this week in Berkeley and Jefferson Counties, and next week in Hampshire County .  Control of second generation should be implemented in those orchards where the pheromone trap capture exceeds 5 moths per trap per week.  Recommended options include Intrepid, Esteem, Assail or Calypso at 1150 DD after biofix (2% egg hatch), or Avaunt, Azinphosmethyl (Guthion) or Imidan at 1250 DD after biofix (6% egg hatch).  An initial spray of any material should be followed by a second complete application in about 10-14 days, or three additional alternate-row-middle applications 5-7 days apart.  Through June 27, 1084 DD have accumulated since biofix (April 30) at the WVU KTFREC.  Even though biofix was on the same date last year, DD accumulations at this point in the season are about 13 days ahead of last year.

Oriental fruit moth hatch of second generation eggs continues and is estimated at 87% complete through June 27, based on an accumulation of 1606 DD since biofix (April 16) at the WVU KTFREC.  Actual egg hatch is most likely somewhat behind predictions based on DD accumulations, especially on apple.  This is because the egg hatch model developed by Penn State University entomologists is based on development in peach, which is more rapid than in apple.

The best approach is to maintain appropriate spray intervals in those blocks where the pheromone trap capture exceeds 10 moths per trap per week.  Recommended materials include Azinphosmethyl (Guthion) or Imidan on peach, and these materials or Avaunt, Assail or Calypso on apple.

European red mite populations have begun to increase in some orchards, especially where pyrethroids were used earlier for control of periodical cicada.  These blocks should be monitored closely over the next few weeks, as mites can increase to very high levels in a short time with warming temperatures. Monitor the mite population on 5-10 trees of the same cultivar (e.g., Delicious, Fuji , or York ) randomly scattered throughout the block.  Collect 10 middle age leaves from each tree, count the total number of motile mites and calculate the average number of mites per leaf. Using Figure 1, estimate the projected production per acre (harvested bushels) for the affected block.  Select the threshold line on Figure 1 for the appropriate time of the growing season.  For a given time of the growing season and a given estimated crop load, if mites per leaf exceed the threshold then some control is needed, either by predators or by application of miticides. If you are using the alternate-row-middle (ARM) system of spraying to make your miticide applications, reduce the action threshold to one-half the value in Figure 1 since you are only spraying one-half of the tree.  If the mite population does not exceed the action threshold, it should be reassessed within 5-7 days.  If the mites per leaf exceed the action threshold, the predator population should be assessed. The most important predator of mites in the mid-Atlantic region has historically been the black ladybird beetle, Stethorus punctum (SP).  Determine their abundance by counting the number of adults and larvae observed during a 3 minute period, while slowly walking around the periphery of each tree sampled for mites.  Divide the 3 minute SP count by the number of motile pest mites per leaf.  For example:  25 SP adults and larvae divided by 10 motile mites per leaf equals a predator-to-mite ratio of 2.5, which is generally sufficient for biological control to occur. Predatory species of mites can also aid in the biological control of pest mites.  The two most common predatory mites in mid-Atlantic apple orchards are Amblyseius fallacis (AF) and Zetzellia mali (ZM).  AF is similar in size to pest mites, clear to straw colored, oval to pear shaped, and moves rapidly over the leaf surface.  An AF-to-pest mite ratio of at least 1:10 has a good probability of providing biological control.  ZM is smaller than pest mites or AF and lemon-yellow to reddish-orange.  Although there are no validated management thresholds for ZM, populations averaging 2-3 per leaf can reduce pest mite levels.  Determine the average number of predatory mites per leaf on the same leaves sampled for pest mites. If the action threshold has been reached and the predator-to-pest mite ratio is insufficient to provide biological control, then a miticide application is justified.  Options include Nexter (formerly Pyramite), Acramite, Zeal,  Kelthane, Vydate and Vendex.  Savey and Apollo may also be used if at least 28 and 45 days, respectively, remain until harvest.  Since these products act primarily as ovicides, they should be tank-mixed with one of the other miticides if motile mite stages are especially abundant.  The orchard should be checked again in 5-7 days after application to determine if retreatment is necessary.   A different miticide should be used if retreatment is needed.  If the predator-to-pest mite ratio is only slightly too low, a half spray (ARM application) may be sufficient to  allow predators to become abundant enough  to provide biological control.

Japanese beetle adults have been emerging for over a week in area orchards.  The most important threat from this insect is to dwarf and non-bearing apple trees, and to stone fruits near and during harvest.  Feeding injury on apple leaves results in a "lace-like" appearance as beetles consume the leaf tissue between the veins.  Injury to apple fruits is not common and usually only occurs on mature fruits that have already been damaged by some other factor. All stone fruits are highly susceptible to attack as they reach maturity.  Beetles are often found in clusters on fruit that is within two weeks of harvest.  Since feeding may be "clumped" or unevenly distributed, care should be taken in looking at a representative sample before making a spray decision.  Control is recommended if fruit feeding injury exceeds one percent.  Sevin is the most effective material available for control on both apple and stone fruits.  The XLR Plus formulation of Sevin is considered to be less disruptive to mite predators than other formulations.  Other options include Lannate, Provado and Surround.

Potato leafhopper adults, nymphs and injury have been observed in some apple orchards during the past few weeks.  This insect overwinters in the Gulf Coast states and adults are carried to this region on wind currents, which is followed by reproduction throughout the summer.  Adults and nymphs are both yellowish-green to pale green.  This species is more active on the leaf than white apple leafhopper and nymphs will run sideways, whereas nymphs of white apple leafhopper run forward or backward.  Whereas white apple leafhoppers feed on older leaves, potato leafhoppers feed on young leaves, causing their edges to curl and their color to change to light green, then yellow, and finally to brown and necrotic ("hopper-burn").  This insect has also been shown to facilitate the transmission of fire blight.  Although no threshold is currently available, control with Provado, Actara, Assail, Calypso, Vydate, Lannate, or Thionex is recommended if presence is detected on young trees, or where fire blight symptoms have been observed in blocks of susceptible dwarfing rootstocks.

PHEROMONE TRAP COUNTS
WEST VIRGINIA UNIVERSITY KTFREC

RBLR = Redbanded leafroller; STLM = Spotted tentiform leafminer; OFM = Oriental fruit moth; CM = Codling moth; TABM = Tufted apple bud moth; DWB = Dogwood borer; LPTB = Lesser peach tree borer; PTB = Peach tree borer; AM = Apple maggot.
¹In a commercial orchard adjacent to an abandoned orchard near Kearneysville.

PLANT PATHOLOGY
 
Infection periods. We have recorded 18 infection periods to date (Table 1), two occurring since the last Orchard Monitor was published on June 14, 2004. Proper spray timing is a key to good summer disease control.

Table 1. Dates and conditions for infection periods at the WVU - KTFREC, 2004.

Brown rot. Incidence of brown rot fruit infection is proportional to temperature and wetness duration. Optimum temperature range is 72-77 F for infection of peach fruit and infection can occur following only 3 hr of wetness at high inoculum concentrations. Longer wet periods during infection result in shorter incubation periods. Insects (nitidulid beetles and honeybees) also can be important as vectors of the brown rot fungus during fruit ripening, carrying conidia to injury sites produced by oriental fruit moth, Japanese beetle, green June beetle, stink bugs, and other insects, or birds, that injure fruit. Wounded fruit are infected much more readily than nonwounded fruit. Hail damage near harvest can lead to a devastating brown rot problem. At harvest, apparently healthy fruit usually are contaminated with spores or latent infections that, under favorable conditions, may later produce decay during storage and marketing.

Effective control of brown rot depends on attention to orchard sanitation; proper pruning of trees to facilitate drying and penetration of spray materials; monitoring for disease every 3 to 5 days during the preharvest period, being aware of favorable weather and the potential for bird, insect and hail damage; and use of effective fungicides at 7 to 10 day intervals during the preharvest and harvest periods. See page 85 of the 2004 Spray Bulletin for suggested chemicals and rates of application. The sterol-inhibiting fungicides, Orbit, Elite, and Indar, show generally similar performance in preharvest brown rot tests. Fruit treated with Indar right before harvest generally shows less rot in the postharvest environment. Alternation of the sterol-inhibiting fungicides with the new strobilurin fungicide, Pristine 35WDG, may help reduce the risk of the brown rot fungus becoming resistant to the SI's.

Phytophthora Crown, Collar, and Root Rots. This is often the time of year to see trees in various states of decline - from completely dead, or, preferably (in terms of reaching a diagnosis), with weak-looking, yellowish foliage, or stunted growth. Trees may exhibit these symptoms for various reasons, all having to do with some problem in the roots or at the root crown region. When I examine trees with these symptoms, I look for evidence of vole injury, insect (dogwood or lilac borer) infestation, a history of fire blight (if a fire blight susceptible rootstock is involved), opportunity for anoxia (oxygen depletion in the root zone due to high water levels), and presence of obvious fungal tissues such as mushrooms, rhizomorphs, or ascogenous structures. If a canker is present, when I cut into it I look for reddish brown discoloration, often in zones and without any obvious fungal structures. These observations suggest crown rot, which can only be confirmed by isolation of the causal organism, Phytophthora spp., in the laboratory. Test kits that provide color reactions if Phytophthora is present also are helpful for making the correct diagnosis.

Crown rot and collar rot are similar, albeit distinct diseases. The two terms are often used interchangeably with some confusion resulting. Collar rot is a disease of the scion portion of the tree, affecting bark tissues of the lower trunk at or above the soil line. This disease has decreased in recent years due to changing preferences in both rootstock and scion cultivars as well as the practice of raising graft unions above the soil line at planting. Crown rot is a disease of the rootstock portion of the tree, affecting bark tissues of the root crown region (i.e. the point where the roots join the stem) or the primary roots where they attach to the crown. Crown rot has become increasingly important since the 1960s largely because of increased use of susceptible clonal rootstocks. Root rot is a disease of the root system away from the crown region. It may occur along with crown rot or may occur by itself.

Foliar symptoms are general indicators of root or vascular problems. Trees infected with Phytophthora spp. are unthrifty, exhibit poor terminal growth, and may become stunted. Foliage is sparse, yellowish, and may develop an early purple discoloration in autumn. Fruit tends to be small and colors prematurely. Infected trees with visible symptoms usually decline progressively over several seasons and eventually die. Less frequently, trees collapse and die suddenly, usually following an excessively wet autumn or spring.

The fire blight bacterium can cause rootstock cankers on M.26 and M.9 that are almost indistinguishable from crown rot. Fire blight cankers form in July/August following early season blossom and/or shoot infections. Rapid decline of trees on these rootstocks in late summer may be caused by fire blight cankers below the graft union.

Mefenoxam (Ridomil Gold EC) will aid in the control of crown, collar, and root rots caused by Phytophthora spp. on both bearing and non-bearing apple trees. Applications should be made on a preventative schedule before symptoms appear, especially in orchards where conditions are favorable for disease development and weather conditions are favorable. Ridomil should not be expected to revitalize trees showing moderate to severe disease symptoms. Ridomil is not registered for use as a preplanting dip treatment. To achieve most effective suppression of Phytophthora diseases, Ridomil should be applied at the time of planting or in the spring before growth starts. For better results, make another application in the fall after harvest. Ridomil is highly specific and will not control other agents causing similar tree decline symptoms such as other root rots, graft union necrosis (tomato ringspot virus), and vole damage. In general, drench applications are thought to be more effective than spray boom applications because the volume of water used with the drench is more likely to move the fungicide down into the root zone. Do not treat bearing trees that you plan to harvest this season. The restricted entry interval for Ridomil Gold EC is 48 hours.

Dipping the roots of nursery-grown trees into a solution of the fungicide Aliette prior to planting may reduce, but not eliminate, Phytophthora inoculum on infested rootstocks. To use, thoroughly mix Aliette at a rate of 3 lbs/ 100 gallons of water, in the desired volume of water and dip the entire root system for 30 to 60 minutes in the mixture prior to planting.

See our "Current Conditions" Web page for details that are updated at least three times weekly.

HORTICULTURE

Farmers And Truckers Benefit from Farm Bill Program

Truckers, as well as farmers, are benefiting from this year's Agricultural Management Assistance Program (AMA).  The AMA is a USDA Farm Bill Program managed by the Natural Resources Conservation Service (NRCS).  This voluntary program provides cost share assistance to agricultural producers to improve soil, water, and other related natural resources.  Under the program, the USDA Natural Resources Conservation Service (NRCS) offers contracts that provide cost sharing for installation of conservation practices.  Contracts can be as long as ten years.  The cost-share rate for most conservation practices is 75%.  

The Nutrient Management/Litter Transfer Program is one of the components of the AMA.  The program will transfer poultry litter from Grant, Hampshire, Hardy, Mineral, and Pendleton Counties to other counties in West Virginia.  More litter is produced in the five county area than can be safely placed on farmland within the area.  Excess application of litter can result in higher nutrient levels in streams and rivers. 

While excess poultry litter can be an environmental problem, poultry litter applied correctly is a valuable soil amendment that increases soil health and productivity.  Transferring the poultry litter out of the Potomac Headwaters area turns a potential water pollution problem into a valuable resource.  The Nutrient Management/Litter Transfer Program is intended to also promote the practice of extended grazing on land receiving the poultry litter.  Extended grazing reduces the amount of time that livestock are confined thus reducing the need for manure storage and handling.   

Trucks will be needed to transport the litter outside of the Potomac Headwaters area to approved farms. Truckers and poultry litter producers may participate by calling the West Virginia Conservation Agency's Moorefield Field Office's toll-free number, 1-888-354-8837 or 1-888-3litter between 8:00 a.m. and 4:00 p.m. on Monday through Friday.   Farmers wishing to receive poultry litter to apply to their land should contact the NRCS Office in their local USDA Service Center to arrange for an on-site assessment, ranking, and development of a required nitrogen based nutrient management plan.  The plan must be prepared by a nutrient management consultant certified by the WV Department of Agriculture.

Payment will be $2.50 per loaded mile from the sending operation, for single loads of 15 tons or more.  Payment will be $1.70 per loaded mile from the sending operation for single loads of 10 to 14.9 tons.  NRCS will pay a maximum mileage of 200 miles per load. 

Land eligible for applying litter must be pastureland, hayland or cropland.  Litter cannot be applied within 50 feet of a river, stream, pond, sinkhole, stream, or property boundary; nor within 100 feet of a well or spring.  Land in all West Virginia Counties, except for Greenbrier and Monroe, is eligible but a priority I ranking score will be given to the following counties:  Barbour, Berkeley, Braxton, Calhoun, Doddridge, Gilmer, Harrison, Jefferson, Lewis, Marion, Monongalia, Morgan, Nicholas, Pocahontas, Preston, Randolph, Ritchie, Taylor, Tyler, Tucker, Upshur, and Webster. Land within a 10-mile radius of a BUTA poultry operation or Danese in Fayette County is ineligible due to Bio-security concerns.  Other Bio-security areas may be identified at any time by the Commissioner of Agriculture.

Priority will be given to those landowners with a planned Prescribed Grazing System and to landowners with an extended grazing plan.  Litter will be transferred directly from the producer's site to the farm of intended use.  Litter is not to be resold or fed to livestock.  If not spread on land within three days of delivery, the stored litter must be covered to protect it from precipitation.

"Applications are being taken now in USDA Service Centers throughout West Virginia," stated Lillian V. Woods, State Conservationist for the USDA Natural Resources Conservation Service (NRCS).  "Interested farmers are encouraged to apply as soon as possible, as the next ranking period to evaluate applications will end on July 9.  Applications will continue to be taken after that date and will be considered if funds remain available."

AMA sign-up information is on the internet on the NRCS West Virginia homepage at www.wv.nrcs.usda.gov or is available from local Natural Resources Conservation Service, Farm Service Agency, West Virginia Conservation Agency, West Virginia Department of Agriculture or West Virginia Conservation District offices.   NRCS and FSA are co-located in USDA Service Centers.  The telephone number is listed under the Federal Government in the blue pages of telephone directories.

Organic and Truck Farmers Eligible for Cost-Share Program

Irrigation, limiting deer damage and other practices important to sustainable organic and truck crop farms are eligible for cost-sharing under the Agricultural Management Assistance Program (AMA).

NRCS is accepting applications for the Agricultural Management Assistance Program (AMA).  The cut-off date for the current ranking period is July 9, 2004.  Applications will continue to be taken after that date and will be considered if funds remain available.   

AMA is one of the few USDA programs that offer cost-share to sustainable organic and truck crop farms.   AMA is supporting sustainable organic and truck crop farming by reducing the risks associated with both the transition to organic farming and commercial truck crop farming.  Assistance can include improving soil health, implementing use of organic soil amendments, developing sources of water for irrigation, developing irrigation systems, controlling soil erosion, managing surface water run-off, installing buffers, limiting wildlife damage by constructing deer fence, constructing composting facilities, and implementing weed control, using cover crops and mulching, and more.

NRCS conservationists can help producers determine which eligible practices will best help the producer to solve the unique resource concern for their operations.   

To be eligible, the organic or truck crop farm must be a commercial operation and must have a West Virginia Agriculture Business and Revenue license.  Eligible crops for this program include vegetables, fruits, nuts, berries, grapes, herbs, flowers, nursery crops, organic grains, and organic hay.  The maximum amount of contract acreage is 20 acres.

The AMA program is available only in 15 states where participation in the Federal Crop Insurance Program has been historically low.  West Virginia and 11 other states in the northeast U.S., and three states in the west are eligible to participate.

AMA sign-up information is on the internet on the NRCS West Virginia homepage at  www.wv.nrcs.usda.gov or is available from local Natural Resources Conservation Service, Farm Service Agency, West Virginia Conservation Agency or West Virginia Conservation District offices.   NRCS and FSA are co-located in USDA Service Centers.  The telephone number is listed under the Federal Government in the blue pages of telephone directories. 

Summer Pruning and Training

"Pruning means removing parts of a fruit tree in order to influence its natural growth in such a way that it will bear as much fruit as possible, will produce fruit more regularly, and will produce fruit of better quality than if it were not pruned." (H. Jonkers)

Fruit tree leaves and shoots seek sunlight and therefore vegetative growth is strongest at the top and periphery of the tree.  A principle goal of summer pruning is to prevent excessive shading of fruit in the interior of the tree.  This can be accomplished by bending branches and/or by removing upright vigorous growing shoots.

In young vigorously growing trees, summer is a good time to "shape" the tree by spreading the selected  framework branches and pruning out the vigorously growing shoots in the canopy.  If, however, growth is inadequate, training may be appropriate but pruning should be approached with caution.

In bearing trees, summer pruning can be used to balance the leaf to fruit ratio.  If it happens to be an off-year, summer pruning can be used to adjust the foliage:fruit ratio and allow sunlight to reach interior fruit.  Summer pruning has also been shown to increase calcium levels in fruit thus helping to reduce bitter pit.  If apple trees have a full crop, prune them lightly in August to increase light penetration and fruit color development.  Removal of vigorous upright shoots from tree centers several weeks before harvest will increase the "red blush" on peaches. 

To avoid sunburned fruit and reduced fruit size from removal of too much foliage, a good rule of thumb is to remove no more than 15% of the tree canopy when summer pruning.

READ THE LABEL CAREFULLY AND USE THE CHEMICALS IN ACCORDANCE WITH LABEL CAUTIONS, WARNING AND DIRECTIONS. REQUEST A MATERIAL SAFETY DATA SHEET (MSDS) FROM THE MANUFACTURER FOR EACH PRODUCT YOU USE.

The West Virginia University Cooperative Extension Service, U.S. Department of Agriculture, West Virginia County
Boards of Education and County Commissions Cooperating.  Equal Opportunity / Affirmative Action Institution