July 12, 2004

Oriental fruit moth hatch of second generation eggs was completed last week and hatch of third generation eggs is beginning, based on degree day accumulations.  Third generation egg hatch is estimated at 6% complete through July 11 on peach, based on an accumulation of 2009 DD since biofix on April 16.  This generation poses a threat to peach fruits near or during harvest.  Larvae can enter anywhere on the fruit, resulting in the exudation of gum and frass (excrement) from the wound area.  As the gum ages, a sooty mold may form on it, turning the entire wound area black.  Larvae can also enter the fruit through the inside of the stem, and therefore leave no evidence of entry except for a small mark at the stem end of the picked fruit.   Control of the third generation is justified where the pheromone trap capture exceeds 10 moths/trap/week.  On peach, an insecticide application is recommended at 2100-2200 DD after biofix (10-20% egg hatch).  A second application at 2450-2500 DD after biofix (50-56% egg hatch) may be needed, depending upon pest density and proximity to harvest.  Control options [days to harvest] include azinphosmethyl (Guthion) [21], Imidan [14], Intrepid [7], Lannate [4 on peach, 1 on nectarine], and carbaryl (Sevin) [3]. On apple, actual egg hatch is falling behind degree day based predictions.  The best practice for the remainder of the season is to treat apples within 7-10 days of exceeding the above trap threshold and to maintain spray intervals on a 2 week (complete) or 5-7 day (alternate-row-middle) schedule for as long as this condition continues.  Recommended options include the same materials as on peach, or Avaunt, Assail or Calypso.

Codling moth hatch of second generation eggs is estimated at 23% complete through July 11, based on an accumulation of 1415 DD since biofix on April 30 at the WVU KTFREC.  In those orchards where the pheromone trap capture has exceeded 5 moths per trap per week, an insecticide should have been applied at 1250-1300 DD (6-10% egg hatch).  A second application is recommended at 1550-1600 DD (45-53% egg hatch), if needed.

Western flower thrips (WFT) is a potential threat to peach and nectarine fruits near harvest, especially if weather conditions become dry.  WFT adults are slender, about 1/16 inch long, yellowish, and hold their wings over their backs.  Larvae are smaller and wingless, but otherwise resemble adults.  Several generations occur per year as populations buildup in white clover and other weeds in and around orchards, as well as in field crops such as alfalfa.  Flight activity of WFT peaks in July through September in stone fruit orchards.  With continued dry weather, ground cover hosts will become less attractive and make it more likely that thrips will move to stone fruit trees. Feeding on fruit near harvest results in silvering injury, a benign surface blemish that can be quite extensive if thrips populations are unchecked.  Injury usually occurs in protected sites, such as in the stem end, the suture, under leaves and branches that contact the fruit, and between fruit.  Inspect the earliest maturing varieties during final swell for silvering injury.  Monitor thrips by counting adults on 10 fruit at 5 locations in the orchard.  Sample fruit from the ends of branches in the lower third of the tree canopy.  Five adult thrips per 50 fruits and the presence of silvering injury may justify control, depending upon the potential market, because extensive silvering can result in downgrading of the fruit.  Control options [preharvest interval] include SpinTor [14 days on peach, 1 day on nectarine (Section 24C label in Virginia and West Virginia )] and Lannate [4 days on peach, 1 day on nectarine (Section 24C label in Virginia and West Virginia )].

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 20 infection periods to date (Table 1), two occurring since the last Orchard Monitor was published on June 28, 2004. Proper spray timing is the key to good summer disease control.

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

This week (July 12 - 16). Favorable disease weather consists of daytime temperatures in the 80's, extended dew periods, and frequent heavy rainfall. These temperatures and extended wet periods provide conditions that are ideal for fungal development and the initiation of disease. For optimum disease control under these conditions: 1) shorten intervals between fungicide applications; 2) when a rate range is provided for a fungicide, select the higher end of the range; and 3) select products that may be more effective than what you have been using. For the relative effectiveness of apple and peach fungicides, consult Tables 1 and 2 in the 2004 Spray Bulletin.

Apple summer diseases. Sooty blotch and flyspeck may soon be visible at some locations, and fruit are entering their period of highest susceptibility to rot diseases. Remember that Topsin-M is weak against the fungi that cause bitter rot. For good control of bitter rot, you will need a full rate of protectant, i.e. 8 lbs./acre of captan 50W or 4 lbs./acre captan 50W + 4 lbs./acre of ziram 76W (the mixture is helpful if you are approaching the seasonal maxima for captan and/or ziram). The addition of a ½ rate of Topsin-M to the full rate of protectant will enhance control of white rot, black rot, sooty blotch and flyspeck while maintaining optimal control of bitter rot. Flint and Sovran are excellent for sooty blotch and flyspeck and good against white rot and black rot. Under heavy disease pressure, Flint and Sovran may not give satisfactory results against bitter rot. Regular and thorough scouting for early disease onset is essential to choosing the right fungicide program and may help prevent losses.

On Nittany, remember that this cultivar is highly susceptible to bitter rot, so use the full rate of protectant fungicide; also continue to apply calcium chloride (6 lbs./acre) through the end of September to minimize losses due to Alternaria rot.

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

HORTICULTURE

Tissue/Leaf Analysis (Update)

As we enter the prime period (July 15 to August 15) for accurate assessment of tree nutrition status, Penn State Plant Analysis Labs have informed us of a July 1 fee increase to $24 for out of state samples.  This is the first rate increase in more than ten years.  Please contact me if you have any questions as you collect leaf tissue for analysis.

SMALL FRUIT

Japanese Beetle Control in Brambles and Blueberries

Biology and life cycle

The Japanese beetle, Popillia japonica Newman, can be a serious pest of blueberries and brambles.  These insects have one generation a year. The larvae can be confused with other white grubs, such as the Oriental beetle (Exomala orientalis Waterhouse), Asiatic garden beetle (Maladera castanea Arrow) and the May-June beetles (Phyllophaga spp.).  Differentiation between these species is based on patterns of hair on the underside of the last abdominal segment.  All have one generation per year, except the May-June beetle, which has a two to three year life cycle. 

Larvae reside in the soil and feed on young roots and root hairs of many plants, such as grasses.  Pupation occurs in late May or early June and adults are present from June until August. Emerging adults release an aggregation pheromone, which results in the congregation of large numbers of Japanese beetles. In addition, a sex pheromone is released by females to attract males. Adults feed on leaves and fruit. After feeding and mating, females subsequently deposit one to five eggs in the soil. This process of feeding, mating, and egg laying repeats until the female has laid approximately 50 eggs. Eggs are deposited at least an inch below the soil surface and hatch after two weeks. The resulting larvae feed until temperatures get too cold. Grubs then remain dormant until spring, when they resume feeding.

Grub control

Insecticides. Grubs are best controlled when they are small and near the soil surface (July to early August).  Large grubs are more difficult to kill and are present in fall and spring. There are no insecticides registered for grub control in brambles or blueberries. However, some states have received a Section 18 emergency exemption for the use of imidacloprid (Admire 2F) in blueberries. In order for this compound to be effective the following are necessary:


    ●    Pre- and post-treatment irrigation,
    ●    apply in evening hours (to prevent UV degradation), and
    ●    apply in early June to mid-July to target first instar larvae.   

Imidacloprid (Admire 2F) has low toxicity to birds and fish and is not fast acting. Please consult your local Cooperative Extension Service office for effective rates and application methods for Admire 2F.

Cultural control. The presence of row-middle sod should be limited, because it provides a reservoir for grubs. A Michigan study found reduced numbers of grubs in areas where the ground had been rotovated compared to areas with permanent sod. In another Michigan study, adult females spent less time digging (to lay eggs) on mowed buckwheat than on buckwheat that was not mowed.

Biological control. Entomopathogenic nematode species such as, Heterorhabditis bacteriophora, at one to two billion per acre, has been shown to be effective in controlling Japanese beetle grubs in turf grass. For additional information on the use of this nematode please visit www.oardc.ohio-state.edu/nematodes/.  Milky spore products available from St. Gabriel Laboratories may also be effective in controlling grub populations (see www.milkyspore.com).

Adult control

Insecticides.  In blueberries, adults can be controlled with broad-spectrum insecticides such as phosmet (24 hr. REI, three day PHI), carbaryl (12 hr. REI, seven day PHI), and malathion (12 hr. REI, one day PHI).  Azadirachtin (4 hr. REI, 0 day PHI) is also available and some formulations are OMRI certified. In some states, imidacloprid is also registered for use in blueberries under Section 18 emergency registration. In brambles, carbaryl, malathion, and azadirachtin are available (and have the same PHI and REI intervals). Please consult your local Cooperative Extension Service office for effective rates and application methods. The broad-spectrum insecticides have longer residual activity and are fast acting. In heavy infestations, sprays may be needed every five to ten days.

Non-Chemical Methods. Although labor-intensive, adults can be hand-picked off bushes and placed in soapy water. This method is more effective on the first group of newly emerged adults, which are capable of attracting many more beetles. Traps baited with lures can be an effective control, but are generally not recommended because more beetles are attracted to an area. Often adults are too numerous and a chemical must be applied.

In a Michigan study, more adults were captured on borders of plots than in the interior, which suggests that effective control on a farm may not prevent a Japanese beetle infestation. Nearby areas with preferred host plants could be the source of unwanted beetles.

Source: Dr. James Barry and Dr. Sridhar Polavarapu, Rutgers University

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