Insect & Disease Control

John F. Baniecki Ph.D.
WVU Extension Service
Plant Pathology/Entomology Specialist
10/1998

Controls by plant

Controls by Insect

Controls by Disease

Bean Aphids Anthracnose
Broccoli Cabbage Maggot Bacterial Wilt
Cabbage Cabbage worm Blossom-end Rot
Corn Colorado Potato Beetle Crown Rot
Cucumbers Corn Earworm Early Blight
Melons Flea Beetle Foot Rot
Onion Japanese Beetle Fusarium Wilt
Pumpkins Leaf Hopper Late Blight
Rubarb Mexican Bean Beetle Neck Rot
Squash Potato Flea Beetle Root Rot
Tomato Rhubarb Curcullio Scab
Spotted Cucumber Beetle
Squash Vine Borer
Striped Cucmber Beetle

Bean

Mexican Bean Beetle: Chewing insect, adult 1/2-inch long, worm 1/3-inch long. Orange beetle with black spots on back. Fuzzy or spiny, yellow worms. Dust or spray underside of leaves when insects are seen. Use Carbaryl (Sevin), Diazinon, or Methoxychlor. Repeat application as needed.

Anthracnose (disease): Brown sunken or craterlike spots on bean pods. Rotate crops. Plow down old bean tops as soon as harvested. Buy western grown, certified seed. Do not harvest when plants are wet. Spray or dust on upper and lower leaf surfaces. Use Daconil 2787.

Root Rot (disease): Stunted, yellow plants. Wilting. Decayed or rotted root system. Rotate crops. Delay planting until soil has warmed up. Plant shallow (1/2 to 1 inch). Treat seed with Captan. Hill beans to stimulate root growth.

Cabbage, Broccoli, Cauliflower

Cabbage worm: Chewing insect 1-1/4 to 1-1/2 inch long. Green worms. Holes in leaves. Dark brown pellets or droppings. Apply Bacillus thurunguensis (Dipel, Thuricide, Bactur, SOK-Bt Biotrol) to underside of leaves as soon as plants begin to grow. Follow directions.

Cabbage Maggot: Chewing insect 1/4- to 1/3-inch long. Yellowing, stunted plants. Roots with holes or tunnels, causing rot. Apply Diazinon 25% EC at 4.5 ounces in sufficient water to achieve thorough coverage. Apply to soil and incorporate immediately priot to seeding or transplanting.

Sweet Corn

Corn Earworm: Chewing insect 1-3/4 inch long. Green, brown or pink worm with light strips along sides and on back. Dust or spray Carbaryl (Sevin) when 10% of ears show silk. Apply into ear zone. Repeat in three days.

Japanese Beetle: Chewing insect 1/4-inch long. Shiny, metallic-green beetle. Dust or spray silks when necessary with Sevin.

Potato Flea Beetle: Chewing insect 1/16-inch long. Tiny black or brown, jumping beetle. Numerous tiny holes in leaves. Leaves turn brown. Spray or dust when plants are 3-4 inches tall. Repeat weekly. Use Sevin.

Colorado Potato Beetle: Beetle 3/8-inch long; worm up to 3/5-inch long. Adult, yellow with black stripes. Worms, brick-red, humped back. Hand-pick beetles and crush egg masses. Bacillus thurunguensis (Bt), M-One strain, Carbaryl (Sevin), Diazinon, or Methoxychlor. Consider Rotenone for hard to kill (resistant) beetles. Alternate chemical pesticides to avoid resistance. M-One controls early larval stages, NOT the adult. Treat when insect or damage appears.

Leaf Hopper: Sucking insect, up to 1/8-inch long. Green, wedge-shaped. Fly quickly when disturbed. Cause marginal browning, rolling leaves. Noticable in July, during hot, dry weather. Use Methoxychlor or Diazinon. Repeat weekly or as needed.

Aphids: Sucking insect 1/6-inch long. Tiny green, powdery blue, black, or rose-colored, soft-bodied insects. Found in numbers on underside of leaves, causing curling, distortion, and stunting. Spray or dust as soon as plants are set out. Use Malathion or Diazinon.

Early Blight (disease): Small black or dark brown spots on lower leaves. Spots enlarge, leaves turn yellow. Excessive leaf drop. Plant clean tubers. Rake and burn plant debris. Use Copper fungicide, Mancozeb, or Daconil 2787.

Late Blight (disease): Water-soaked areas on leaves turn brown. Eventually, entire leaf blighted. Tubers discolored inside. Plant disease-free tubers. Do not dig tubers from diseased plants until tops are dead. Use resistant varieties.

Scab (disease): Raised scabby areas on tubers. Plant scab-free tubers in scab-free soil. Maintain soil pH at 5.2 or slightly below. Use resistant varities. Plow down green cover crop.

Tomato

Flea Beetle: Chewing insect 1/16-inch long. Tiny, black or brown jumping beetle. Numerous tiny holes in leaves. Leaves turn brown. Spray or dust with Sevin when plants are 3-4 inches tall. Repeat weekly.

Aphids: Sucking insect 1/6-inch long. Tiny, green, powdery blue, black, or rose-colored, soft-bodied insects. Found in numbers on underside of leaves, causing curling, distortion and stunting. Spray or dust as soon as plants are set out. Use Malathion or Diazinon.

Blossom-end Rot (disease): Blackened area on blossom-end of fruit. Plant in well-drained soil, high in organic matter. Avoid excessive nitrogen. Maintain uniform soil moisture. Mulch plants. Do not cultivate deeply.

Early Blight (disease): Small black or dark brown spots on lower leaves. Spots enlarge, leaves turn yellow. Excessive leaf drop. Disease moves up the plant. Rotate crops. Spray as soon as plants are set out. Use Copper fungicide, Mancozeb or Daconil 2787.

Late Blight (disease): Water-soaked areas on leaves turn brown. Eventually, entire leaf is blighted. Rot on fruit. Spray Mancozeb or Daconil 2787. Complete coverage is necessary.

Fusarium Wilt (disease): Wilting or drooping of plant. Use VFN-resistant varieties.

Cucumbers, Squash, Melons, Pumpkins

Striped Cucmber Beetle, Spotted Cucumber Beetle: Chewing insect 1/5-inch long. Yellow beetle with black spots or stripes on back. Treat when seedlings emerge. Treat entire planting at five-day intervals, as needed. Use Rotenone or Sevin. Spray or dust toward evening when bees are not pollinating. Sevin may kill bees when applied between 10 a.m. and 2 p.m. To avoid injury to tender foliage, do not apply when rain or humidity is expected during the next two days.

Squash Vine Borer: Chewing, white worm, 1 inch long. Find point of injury. Split stem along side and puncture worm. Mound moist soil around cut to induce root growth above cut. Spray or dust with Methoxychlor when runners develop. Repeat weekly.

Bacterial Wilt (disease): May show wilting on outer ends of vines or entire vine. Bacteria carried by cucumber beetles. Use insecticide (see above) to control beetles. Begin spraying as soon as plants emerge, or when soil cracks.

Rhubarb

Rhubarb Curcullio: Chewing insect 1/2 to 3/4 inch long. Yellow dusted, snout beetle. Adult beetles bore into stalks, crowns, and roots. Attacks wild dock (coarse weed). Burn all infested plants. Destroy wild dock in July, after beetles lay their eggs.

Foot Rot or Crown Rot (disease): Brown sunken spots on base of leaf stalks, decayed stalks, wilted leaves. Disease spreads rapidly in row. Dig out and burn diseased plants. Do not scatter infested soil.

Onion

Neck Rot (disease): Soft rotting of onion neck. Becomes watery and foul-smelling. Yellow and red types rot less than white onions. When harvesting, cut tops close and dry stubs before storing. If possible, dry for two to three days with heat at 90O to 120O F. Discard thick necks and scallions. Store in slatted crates in a dry, well-ventillated area at 32O F.