Abstract:
Eighteen apple and five peach growers, located in the counties of Erie, Huron, Lorain, Ottawa, and Sandusky, enrolled 29 blocks of commercial production. Insect pests monitored with pheromone traps included spotted tentiform leafminer (STLM), codling moth (CM), apple maggot (AM), San Jose scale (SJS), peach tree borer (PTB), redbanded leafroller (RBLR), Oriental fruit moth (OFM), tamished plant bug (TPB), and lesser peach tree borer. Other fruit tree pests monitored by scouting were various aphids, leafhoppers, and European red mites.
Additional orchard monitoring verified the presence of the following: Stethorus punctum, syrphid fly larvae, lacewing, Cecidomyiid larvae, phytoseiid mite ('fallacis'), and various ladybeetles. Of particular interest were the populations of Stethorus as a biological agent for the control of European red mite. The following project objectives were followed as reporting guidelines for this Mini-grant:
1 . To test the Penn State guidelines for Altemate Row Middle spray system.
2. To identify beneficial arthropods and monitor populations.
3. To study the effect of pest control measures on beneficial arthropod populations.
4. To evaluate the economic benefit of biological control made possible by protecting
beneficials.
Based on orchard observations made in the early to mid-Seventies in SE Pennsylvania, the alternate
middle spraying has been encouraged by Penn State as a means of protecting Stethorus punctum
and predacious mites in apple orchards. Applications of insecticides and miticides are made to
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alternate tree rows with a follow-up to unsprayed rows three or four days later. This spray application
method should allow a protective refuge in the unsprayed trees while the pesticides degrade in the
sprayed rows.
Three growers utilized the alternate row middle (ARM) method in a portion of their orchards. Grower
#1 tried ARM in a block of young Red Delicious in their second year of production. Grower #2 utilized
ARM in an older block of Red Delicious where heavy pressure from European red mite has been a
historic fact. Grower #3 normally uses ARM throughout his blocks when applying insecticides and/or
miticides but not for disease control.
Results of observations of Stethorus punctum neither support nor discourage ARM. Stethorus
punctum were present in 24 of the 25 monitored apple blocks with populations apparently dependent
upon European red mite (ERM) pressures. Stethorus punctum mobility was evident in ARM blocks
as well as other blocks. This mobility was displayed by their ability to move into areas with sufficient
ERM populations to encourage female Stethorus to lay eggs, and when ERM numbers were
controlled to move to other areas or blocks.
A review of the early Pennsylvania work with ARM indicated a concern over the use of the acaricide
Plictran (cyhexatin). This material, though rate dependent, was considered harmful to beneficials and
of limited value in IPM programs. Fortunately, newer materials including both miticides and
insecticides have found widespread usefulness by protecting apple crops without more than low to
moderate effects on beneficials including Stethorus punctum. In other words, an IPM program can
be designed around chemical as well as biological control of ERM while reducing the need for refuge
said to be afforded with ARM.
The percentage of blocks where beneficial insects and/or predator mites were found increased from
59% in the late spring to 100% by mid-August. Some beneficials were found during orchard scouting
during each of the 17 weeks from May through August.
One orchard block, owned by a grower more interested in 100% pest control rather than protecting
beneficials, inadvertently become the "worst case" example for comparison with all other blocks.
Beneficials were found during only 4 weeks with no populations of Stethorus punctum ever found.
The savings from one spray application deleted in the IPM program would approximately equal the
grower cost in the program. Producers saved from one to five applications when comparing their
records with a standard spray calendar based on a 7- to 10-interval. A harvest survey showed
negligible fruit damage caused by direct feeders though some disease damage from sooty blotch
and fly speck was found.
Extension Program Implementations:
Grower's continue to financially support and participate in a program that make sense economically,
allows for the production of high quality fruit, and combines biological pest control with judicious use
of pesticides. An evaluation instrument completed by 90% of the growers indicated a high level of
satisfaction with programming targeting a specific need. One other small measure of success -
growers indicated that they are more likely to use the advice available from Extension sources,
including scouts and the weekly newsletter, than the advice traditionally available from sales
representatives of chemical companies.
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