Weekly Field Crops Pest Report 2008
View from the Field
Potato leafhopper (PLH) was OVER threshold in 15 inch alfalfa at the Cornell Research Farm at Valatie. PLH numbers were over threshold (145 PLH in 6 samples) and there were both nymphs and adults found in the field.
The alfalfa is starting to show the typical signs of PLH damage with the v-shape yellowing on the tips of the leaflets.
Jeff Miller (
Weather Outlook July 3, 2008
Temperatures this past week were near, to just a couple of degrees
above normal. Areas in the Western Finger Lakes and
A relatively quiet weather pattern appears to be unfolding as
a couple areas of high pressure will keep a stalled front to the
south. This front will come through today and stall out tomorrow
over the Mid Atlantic. Meanwhile, high pressure will come in Friday.
The models have been trending towards keeping this high over us
through the weekend into Monday. This will keep that front, and
the rain associated with it, mostly south of
Aphid Mummies in Alfalfa
Walking fields is critical to early detection of crop problems. It's also a way to discover all sorts of interesting examples of ecology in action. One such example, common in alfalfa this time of year, is the presence of what might appear to be bronzed colored aphids "resting" on alfalfa leaves. "Resting aphids?" What are you really seeing? One type of biological control of pea aphids
Pea aphids [Acyrthosiphon pisum (Hemiptera: Aphididae)] tend to be found in low to modest numbers in NY alfalfa but are generally not an economic pest. These insects are a food source by many natural enemies such as lace wing and lady bird beetle larvae. The bronze colored "resting" aphids one may see on alfalfa leaves are aphid "mummies" the result of the aphid being parasitized by a type of tiny wasp. In NY, two types of wasps can be found: Praon pequodorum and Aphidius ervi both Hymenopterans in the family Braconidae.
Praon pequodorum is a native aphid parasitoid which includes
the pea aphid in its host range. Aphidius ervi was introduced
Who's who? Aphidius mummies are smooth. Praon mummies look like they have webbing around them, with the bronze colored aphid body sitting on top. See photo.
How did that happen?
When the female wasp finds a suitable host, she bends her abdomen under her legs and injects an egg in the aphid with her ovipositor. Aphids may continue feeding and reproducing for several days, until the egg hatches. When the egg hatches, the wasp larvae starts to eat the aphid from the inside and the larva completes its life cycle in the aphid body. Effective parasitization is obvious when the aphid swells and hardens into a leathery, brown colored "mummy". The parasite completes it's life cycle by emerging as an adult through a round hole at the rear of the mummy. Mummies can usually be seen 14 - 21 days after the first introduction is made. Development time is dependent upon the temperature and other environmental factors. One female wasp lays about 350 eggs in a lifetime. Most of these eggs are laid in the first five days after introduction.
The life cycle of Apidius ervi described above is excerpted from "Biological Control of Aphids with Aphidius ervi" by Cathy Thomas (PA Dept Ag IPM Program). The Vegetable and Small Fruit Gazette, April 2001, Volume 5, No. 4.
Note: Species of Aphidius and Praon have also been found to attack soybean aphids in NY - watch for mummies....
Soybean Defoliators: Do They Do Damage?
Japanese beetle and Mexican bean beetle are the main defoliators of soybeans in NYS. While they are minor pests, defoliation of soybeans sends up many red flags by growers. The question normally is how much leaf defoliation is too much in soybeans? The good thing is that soybeans can withstand much defoliation without losing yield. The soybean defoliation threshold is 35 percent of leaf area eaten or missing from V1 to just before bloom. During blooming through pod-filling stages, the threshold is 20 percent defoliation. The following pictures are a guide that depict 10, 20, 30 and 40 percent defoliation:
Predators in Field Crop The Rest of the Story:
Lady Beetle Larvae
I have been asked many times if this is a pest! I have also been asked if they bite! If you have never seen a lady beetle larva they look rather intimidating. Some people think they look like tiny alligators. So to answer the questions above they are a very effective beneficial insect and beware if you are a food source like aphids and other small insects they do bite!
Lacewing (several species)
Adults feed in the evening or night on nectar, pollen, and aphid honeydew. Larvae are very active predators of aphids and other small insects in many agricultural crops. Adults are light green with long, slender antennae, golden eyes and have large lace-like wings that are 1/2 to 1/3 inches long. Larvae are called antlions, and look like a little green-gray alligator. Antlions have sickle-shaped jaws, that penetrate the prey, inject a paralyzing venom, and then suck out the body fluids of the victim. The larvae will reach about 1/2" long before they pupate.
Damsel Bugs (Nabidae)
Damsel bugs, also known as nabids, eat small insect eggs as well as aphids and mites. This insect uses a needle like mouth-part to insert into its prey and suck out the insides. They are slender, often yellowish-brown and about 8 -12 mm (3/8 to 1/2 inch) long. The wings lie flat across the back, crossing at the tips. The abdomen is slightly swollen and the body tapers toward a narrow, elongated head. The adult female inserts white colored eggs into the stem of the plant --only the egg cap shows. Damsel Bug nymphs are a little smaller than their parents, do not have fully developed wings, but otherwise resemble wingless adults in shape and color. Be a little careful with damsel bugs because they are predators and can give a painful bite to big and small alike.
Adult syrphid flies, also known as flower flies, like to feed on nectar and pollen of several kinds of flowers. Many species of adult syrphid flies look like bees. After the adults feed they lay 100s of white 1mm long eggs in the mist of aphid colonies. Syrphid fly larvae are good predators of aphids and other soft-bodied insects. Larvae are legless maggots that are green, yellow or gray with a yellow or white stripe down their back. For pictures of syrphid flies view this website: Syrphid Flies
NYS Soybean Rust and Soybean Aphid Update
Sentinel plots in
Since the beginning of 2008, soybean rust has been reported on
kudzu in one county in Alabama; eleven counties in Florida (two
of these counties had reports on coral bean and snap bean and one
had a report on soybean); three counties in Louisiana; one county
in Mississippi, and three counties in Texas. Reported infected kudzu
sites in many counties have been destroyed. Rust was also reported
in three states (5 municipalities) in
NY State Soybean Rust Hotline: 607-255-7850
* Emergency contact information ("911", local hospital, Chem. Spill emergency contact, other?) posted in central posting area
* Maintain crop records by field, including variety, planting date, pesticides used, nutrient inputs including manure, yields, etc.
* Watch for winter annual and other early season weeds, any patches of herbicide resistant weeds?
* Determine plant populations, make notes on early season problems, growth stage
* Gaps in row? Check for seed corn maggot, wireworm, cutworm, armyworm, seedling blights, birds, seed placement issues
* Check no-till fields/fields with high residue or weeds for slug damage, cutworm, armyworm
* Monitor for weeds, note presence of "who", "how many" and "where"
* Check herbicide resistant corn fields for herbicide resistant soybean
* Adjust post emergence weed control actions
* Monitor winter grains for crop stage (grain maturity), insect problems (cereal leaf beetle, armyworm) and foliar / head diseases
* Evaluate crop for timing harvest
Alfalfa & Hay:
* Monitor alfalfa seedings for weeds, insects & diseases.
* Check regrowth of established alfalfa stands potato leafhopper, weed and disease problems.
* Storage areas cleaned and ready to accept next harvest?
* Evaluate stand emergence - seedling blights, seed corn maggot, weed assessment, soybean aphid
* Check herbicide resistant soybean fields for herbicide resistant corn
Dairy Cattle: Livestock Barn Fly Management:
* Sanitation, sanitation, sanitation - clean animal resting areas, feed troughs, minimize source of moist organic matter i.e. fly breeding areas in barn and in adjacent animal loafing yard
* Check waterers, drainage, roof gutters for leaks and potential overspill
* Begin fly monitoring: install "3X5" index card fly speck monitoring cards through out barn
* Order fly management materials: fly tapes, insecticide baits, natural enemies (parasitoids)
* Continue release of purchased natural enemies (fly attacking parasitoids)
Dairy Cattle: Pasture Fly Management:
* Monitor animals for presence of face flies, horn flies and stable flies.
* Check feed bunk / water source locations for signs of stable fly breeding (moist undisturbed organic matter spilled feed, round bales, etc.) , minimize source of moist organic matter i.e. fly breeding areas in barn and in adjacent animal loafing yard
* Check paddocks for forage quality / quantity, rotate as appropriate
* Check paddocks for vegetation poisonous to livestock
* Consider use of fly traps to help reduce deer, horse and stable fly populations
* Keep areas around storage bins and silos clean and mowed
* Note any repairs needed for recently used equipment: tractors, tillage implements, planters, etc. as they are cleaned and serviced.
* Service corn and soybean planter as needed. alfalfa harvesting equipment, and tillage implements
* Calibrate manure spreaders - maintain records on amount spread per field
Up Coming Events
Seed Growers Field Day
Weed Science Field Days
*Wednesday, July 16, 2008
Keith Waldron: NYS Livestock and Field Crops IPM Coordinator
Ken Wise: Eastern NYS IPM Area Educator: Field Crops and Livestock