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Fruits
Volume 58 Number 12 Date 07/24/2014 APPLE MAGGOT - Counts have been low since emergence began four weeks ago and most sites have not reported any flies. The highest weekly total as of July 23 was 15 flies on an unbaited red sphere at Rochester in Racine County. Continued maintenance of traps will be important as harvest approaches in August, particularly for orchards with fruits damaged during recent hailstorms. Baited traps should be concentrated in late summer varieties (i.e., culitvars ripening before Paula Red) for continued monitoring of apple maggot pressure. STINK BUG - Adults and nymphs have been observed on the undersides of leaves in west-central Wisconsin apple orchards, signaling the potential for fruit injury prior to harvest. Growers are encouraged to monitor fruits for evidence of feeding by these insects. A single adult or nymph can injure many apples and damage may not develop until after the fruits are in storage. CODLING MOTH - Most apple orchards are 1,000 or more degree days (modified base 50°F) beyond the first biofix, and treatment for second generation larvae has started. An increase in moth counts from the spring to summer flight suggests that some degree of fruit injury is probable early next month and fruits should be closely inspected for damage. Apple growers are reminded to rotate insecticides between generations to prevent resistance to chemical materials. Localized larvicide applications are usually an acceptable alternative to orchard-wide treatment for sites with variable larval pressure between cultivars or blocks. POTATO LEAFHOPPER - A Fond du Lac County apple grower reports that populations are heavy in some orchard blocks and associated discoloration of new shoots and mild hopperburn symptoms are appearing. One- to two-year-old, non-bearing apple trees are most susceptible to leafhopper feeding and should be monitored for leaf curling and yellowing caused by the adults and nymphs. Treatment is justified at levels of one or more nymphs per leaf when symptoms are evident. SPOTTED TENTIFORM LEAFMINER - The second flight has peaked in most southern and central apple orchards and sapfeeder larvae are reappearing. The economic threshold for the third and final generation increases to five mines per leaf. -- Krista Hamilton, DATCP Entomologist 
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