|
|
|
Fruits
Volume 57 Number 1 Date 04/12/2012 REDBANDED LEAFROLLER - First brood adults have been reported from the southern counties for four or more weeks and peak emergence has already occurred at some sites. A reliable sampling method for this insect is to monitor for larvae on foliage, particularly watersprouts, 10-12 days after the first moth is registered in pheromone traps. Pupae and older larvae can be located by searching for folded leaves. Two important characteristics of RBLR larvae that distinguish it from other leafrollers are the head capsule and thoracic shield (the hardened plate behind the head), which are the same pale greenish yellow color as the rest of the body. Other leafrollers, such as the OBLR, have black or darkened heads and thoracic shields. SPOTTED TENTIFORM LEAFMINER - The first of three flights this season began by March 21 in southeastern Wisconsin. The apple orchards near Beldenville and Hillpoint reported 486-600 moths this week, but elsewhere counts were less than 151 per trap. Peak emergence of first brood adults is approaching and will likely occur next week or the following in southern and west-central Wisconsin orchards. CODLING MOTH - Pheromone traps should be in place to capture the first spring moths expected to appear later this month at locations where 201-340 degree days (base 50°F) have been surpassed. This includes the southern and west-central counties. Daily trap checks are recommended after the first moth appears and until biofix has been established. PEAR THRIPS - Economic populations of this insect were reported last month from an apple orchard near Malone in Fond du Lac County. Counts of 9 or more thrips per cluster were noted on March 21 and controls were applied five days later. According to the report, the insects were concentrated in orchard trees adjacent to wooded lots, but showed no preference for a particular tree variety. Large populations of thrips can cause abnormal leaf formation, leaf tatter, flower injury and reduced fruit set. Pear thrips was documented for the first time in Wisconsin in 1989, in Grant County. Surveys the following year recorded it from 22 counties. Its impact on fruit trees, ornamental maples and maple syrup production is not fully understood. Fruit growers in the state should become familiar with pear thrips and plan for scouting as part of their IPM programs for 2012. GRAPE FLEA BEETLE - Spring migration into vineyards from nearby wooded areas and fencerows is underway. Biweekly scouting is suggested through late April. Feeding by the overwintered adults may damage primary buds at this time of year, preventing shoot expansion and ultimately reducing grape yields. Plants on the margins of vineyards are at greatest risk of injury. Treatment is justified if more than 5% of buds are damaged. --Krista Hamilton, DATCP Entomologist FROST AND FREEZE DAMAGE - Resident Orchard IPM Specialist, John Aue, recommends a foliar nutrient spray to reduce tree stress and accelerate recovery of apple trees damaged by frost this spring. A proposed nutrient formulation has been developed by Ed Stover of Cornell University: https://mywebspace.wisc.edu/armccullough/web/cias/resources/stover_et_al-prebloom_foliar_1999.pdf WARNING: The products referenced in the article could be safely tank mixed with a current fungicide cover without toxicity or incompatibility issues, but other zinc formulations such as zinc sulfate might not be compatible and could cause phytotoxicity. FIRE BLIGHT - Rainfall predicted for the nights of April 13-14 in combination with temperatures in the low 50s could result in fire blight outbreaks by Sunday, April 15. All pruning activities should cease by April 12 to ensure wounds heal before the bacterial growth period. Apple growers with fire blight concerns may apply streptomycin to susceptible varieties 24 hours before or after the forthcoming infection period, on April 13 or 15. -- Information on freeze damage and fire blight provided by John Aue, Orchard IPM Consultant 
|
|