Volume 57 Number 11 Date 06/21/2012
APPLE MAGGOT - The apple orchards near Mequon in Ozaukee County and Rosendale in Fond du Lac County reported their first flies of the season from June 14-20, while 26 other locations reported no activity. Counts ranged from 2-3 flies per trap. Yellow traps baited with ammonium acetate are effective for approximately one week and should then be replaced or rebaited. Red sphere traps may be used with or without fruit essence lure through harvest. The economic threshold for apple maggot is one fly per unbaited trap per week or five flies per baited trap.
EUROPEAN RED MITE - Orchardists should be aware of the possibility of outbreaks under present dry conditions. Trees exhibiting light bronzing can be inspected for adult females on the upper and lower leaf surfaces and eggs near the midrib by using a 10x hand lens. Treatment is recommended if the economic threshold of 7.5 mites per leaf is exceeded.
SPOTTED TENTIFORM LEAFMINER - The second flight has peaked in several southern and central orchards. Extremely high counts of 500 or more moths per trap per week were registered in 8 of 28 apple orchards during the last reporting period. Egg laying is heavy at this time. The economic threshold for second brood leafminers is one mine per leaf.
SAN JOSE SCALE - Continued sampling by taping scaffold branches is advised to determine the relative abundance of scales, the end of the hatching period, and if control treatments applied last month were effective. The tape should be changed every 7-10 days for approximately one more month.
POTATO LEAFHOPPER - Populations have increased considerably this month. Although control may not be justified for orchards expecting a light fruit crop this year, growers are reminded that non-bearing, 1- to 2-year-old trees are very susceptible to leafhopper feeding and this is where scouting efforts should be concentrated. Treatment is warranted at levels of one or more nymphs per leaf when symptoms are apparent.
--Krista Hamilton, DATCP Entomologist