RI Apple Newsletter
July 3, 1998
From Heather Faubert and Steve Alm

Recorded pest message available between 5:00PM and 8:00AM daily. Call (401) 949-0670.
We have been experiencing technical difficulties this past week but it should be up and running on Monday, July 6.

We tried to set up apple maggot traps early this year but we certainly missed the first fly. We started setting up traps June 24 and by June 29 we had caught 6 apple maggot flies on two traps set up in Jersey Macs. In 4 out of 6 orchards checked this week, we found apple maggot flies on traps. Two of the 4 orchards were above the threshold of 1 - 2 apple maggot flies per trap. This is definitely an early season so we expect fruit to be suceptible to apple maggot fly injury earlier than usual. We are also expecting a high number of apple maggot flies migrating into apple orchards this year. Abandoned trees don't have any fruit for the apple maggot flies to lay eggs in so they will migrate sooner than usual.

If you are not monitoring apple maggot flies with red sticky traps we recommend you apply an insecticide now to early maturing varieties, McIntosh and Cortlands. Use half rates of Imidan or Guthion.

Apple blotch leafminer second generation mines are visible now from the under side of leaves and some have begun to show through the top side of the leaf. If you are planning to spray for second generation leafminer it should be applied immediately. Provado is the least harmful to beneficial mites but Lannate and Vydate are also effective against apple blotch leafminer sap feeding mines. The second generation is much more difficult to control than the first generation. The second generation leafminer is more spread out and the trees have many more leaves which makes it more difficult to get good pesticide coverage.An insecticide against apple blotch leafminer should only be applied if you get an average of 1 new mine per leaf.

There are two parasites which attack apple blotch leafminer larvae. In one orchard checked this year 68% of the leafminer larvae were parasitized or dead. An easy way to check on the level of parasitism in your orchard is to look at the underside of tissue feeding mines (those are mines that can be seen from the upper leaf surface). The mines where apple blotch leafminer have emerged have a small, brown pupal case sticking out of the mine. The mines that were parasitized have a small pin point size hole or no hole at all. The mines with no hole either still have a parasite pupa inside or the apple blotch leafminer has died in the mine. It's really very easy to tell - and it's fun!

We are finding many rose leafhopper nymphs in many orchards now. Rose leafhopper looks exactly like white apple leafhopper to the naked eye. First generation rose leafhopper adults migrate into orchards from nearby multiflora rose bushes in early to mid-June. Second generation adults, present in July and August, lay eggs primarily in orchards. Third-generation adults, present in September and sometimes in very large numbers, can cause extensive excrement spotting of fruit and be a nuisance to pickers before migrating to rose bushes to lay overwintering eggs.

Rose leafhoppers, like white apple leafhoppers, are resistant to organophosphate insecticides, Guthion and Imidan. Leafhopper nymphs can be controlled with Thiodan, Provado (1 oz. per 100 gal), or Sevin. Thiodan and Provado are least harmful to beneficial mites where Sevin is moderately harmful, killing 30 - 70% of predators within 48 hours of application.

Another leafhopper we find in the orchard now is the potato leafhopper. These leafhoppers migrate up from the south and west of Rhode Island each year. They feed on terminal leaves and cause these leaves to turn yellow and the edges to turn brown (known as hopper burn). The leaves also cup. This damage is only a problem to young trees because the damage stunts the trees. Newly planted trees and nonbearing trees should be checked for leafhopper feeding. Thiodan or Sevin can be applied to control leafhoppers in young trees. Guthion or Imidan may also control them but often Thiodan or Sevin is needed.

We are finding many beneficial mites in some orchards. The rainy weather has held back the European red mite populations and has allowed the beneficial mite numbers to increase. We are finding many of our little yellow mite predators, Z. mali, and also we are finding quite a few of the predator, T. pyri, which we released in 1996. In two of the orchards where we released T. pyri we are seeing excellent biological control of red mites in most of the block due to T. pyri.

Now that we seem to have moved into warmer, drier conditions we can expect European red mite populations to build. The threshold for July 1 - 15 is 5 motile mites per leaf or 65% of leaves with motile mites. Sample middle-age leaves. When this threshold is reached apply Pyramite. Pyramite should only be used once a season! Also, thorough coverage is essential for good mite control so it should be applied 2x or dilute.

All the wet weather has made it very difficult for controlling apple scab as well as fly speck. We haven't found any fly speck lesions yet this year but we expect to see some soon. Table 14 on page 64 of the 1998 - 1999 Apple Pest management Guide contains information about how much rain is needed to wash off fungicide applications. Topsin M at 3 oz. plus Captan at 2# per 100 can withstand 3 inches of rain.

I received a message from a respectful and courteous hunter looking for private land to hunt deer on. He is willing to pay a small trespass fee or perhaps could develop a web page for the host. His name is Ed Varin at 36 Steere Farm Road in Harrisville. His phone number is (401) 568-0971 and his email address is evarin@tp.net.