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May Pest Calendar Part 1
May Pest Calendar Part 1

Courtesy County Integrated Pest Management Committee

PESTS AND DISEASES

LEAST TOXIC TREATMENT

HARD PESTICIDE

TREATMENT

Fungal Leafspot and Twig Blight on Aspens;

Apricot and Apple Scab on Fruit Trees; Powdery Mildew; Black-Knot on Chokecherry.

Spray with fungicide such as Sulfur to protect against leaf spots or Black-Knot galls that show up later in summer. Keep irrigation water off of leaves!
Spray with Captan or Benomyl if prolonged wet and warm periods occur.
Leafspots on Rose and Phlox. Use antitranspirants (Wiltpruf or Vapor Guard) or Baking Soda (Remedy)

Funginex, Daconil

Rust (fungal) disease on Rose, Hollyhock, Hawthorn, Apple. Keep leaves DRY - remove and destroy infected leaves. Spray Sulfur if leaves wet >4 hrs.

Bayleton, Daconil

Fireblight: Bacterium causes young blossoms, shoots, and fruit to wilt and collapse, turning brown to black. Prune out infected shoots or limbs 6-18" below injured area on a hot, dry day. Sterilize tools between each cut!
Spray with Agricultural Streptomycin during bloom or with Copper after bloom.
Green Aphids


Spruce Gall Adelgid Look for wooly clumps at the base of buds.

Leafhoppers (Virginia Creeper, Rose, and Potato)

Look for white stippling on leaf surfaces.

Spray with Insecticidal Soap if >20% of new growth is infested or spray with Neem. Repeat applications of both may be required.

For aphids: add lacewings or ladybugs if <1 predator is found for every 5 aphids in a 10-branch sample.

Late delayed dormant oil sprays: (see INSECT PREVENTION, page 2).

Spray with Acephate (Orthene) for high numbers of aphids or leafhoppers, or if plants are susceptible to aphid injury (leaf curling) from these pests. Acephate is not labeled for use on food crops.
Birch Leafminer; Lilac Leafminer:

Only treat whitish larva INSIDE birch leaves, causing pale blotches which turn brown and papery.

Use a soil drench of or spray with Neem (trade names are: Bioneem, Azatin, Neemix, or Neemazad);

Abamectin (Avid); or Spinosad (conserve).

Use a "systemic" insecticide such as Acephate when first leafminer larva can be seen inside the leaves.


Spruce Budworm:

1" long, brownish with

ivory spots. Older larvaetie tips of shoots together

to form a "nest".

Spray swelling buds of Spruce, Fir, and Douglas Fir with Bt-K mixed with 1-2 T/gal of Insecticidal Soap, or with rotenone-pyrethrin mix or Neem plus Insecticidal Soap.
Spray with Carbaryl if this pest has killed Spruce terminals previous years.
Western Raspberry Fruitworm: Light brown beetles usually found on leaves and buds, and slender white worm-like grubs on flowers or in fruit damage leaves, buds, flowers, and fruit. Treat only the brown beetles that slit new leaves.

Spray Rotenone pre-bloom.

Till soil around plants in late summer after harvest.

Spray Diazinon EC pre-bloom.
Grasshoppers Nosema locusta (semaspore)
Carbaryl (Sevin) bait (Debug)
Leafroller Larvae (see April) None.
Turf: Sod webworms and cutworms Neem (Turplex)
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