Weekly Field Crops Pest Report 2008
10. Up-Coming Events
View from the Field
Eastern NYS-Ken Wise
This week at the SUNY Cobleskill Farm alfalfa was looking good and was 12 to 15 inches tall depending on the field. There were a lot of dandelions in the alfalfa fields. Alfalfa weevil activity appeared limited with no foliar tip feeding evident and only a few adults or 1st instar larvae found. By contrast plenty of tarnished plant bugs, pea aphids and clover root curculio adults were observed. Beneficial insects were more obvious this week including damsel bugs and 2 species of lady beetles (aka lady bugs)..
Some of the furthest-along wheat fields in western NY are very close to having flag leaf emergence. Powdery mildew was common, and even very widespread, in some fields.
Keith Waldron observed first and second instar alfalfa weevil larvae in an alfalfa stand that was about 16 inches tall in the
Mike Stanyard (western Finger lakes region) reports that broadleaf weeds, including velvetleaf, pigweed, and lambsquarters, as well as annual grass weeds, are about one inch tall in corn fields this week. Mike also observed that heavy early morning dews are likely contributing to disease proliferation in wheat
Last week saw below normal precipitation and temperatures throughout the state. The coastal climate division and lower
There were 25-75 GDD days (base 50) during the period May 7-13 which put the seasonal total in the 100 to 200 range across the state. Compared to last year, the southeastern part of NY is zero to 3 days behind the normal accumulation and the
Insect Pests and Corn Crop Establishment in Conservation Tillage
Overall, IPM and soil conservation are compatible priorities for field crop production. Both depend upon our knowledge of the biological cycles of crops, pests, and soil microorganisms. Both have the goal of protecting soil and water resources while still maintaining or improving farm economic returns. However, there are circumstances in which a unique ecosystem created by soil residue or cover crops can give pests an extra foot-hold in spring. A proactive approach can mitigate any potential negative pest impacts from increased soil cover in a conservation tillage field.
Two insect pests in particular can be a greater threat to our field crops in soil conservation systems, seedcorn maggot and black cutworm.
Black cutworm adult moths must migrate north each spring, and they lay eggs primarily on grasses. When there are grasses in the field overlapping a corn crop, infestation from this pest is more likely. Two scenarios that can contribute to black cutworm population booms include a grass cover crop that is left covering a field until soon before corn planting, and weedy grasses that are not burned down prior to no-till planting. If the grassy weeds are controlled after an infestation of cutworm is already happening, the cutworms will leave the dying weeds and feed on the small corn plants. Risk to a corn crop from black cutworm is increased by planting late. For more information on black cutworm biology and management, please review our online publication, Black cutworm in Field Corn Management Guide.
Adult flies of the seedcorn maggot lay eggs in areas of high organic matter on or near the soil surface. The hatching maggots find their way to the nearby corn seed. The decaying surface organic matter in a no-till or reduced till field can substantially increase the risk of high populations of seedcorn maggot. Reduced tillage keeps soil temperatures lower early in the season. Cool soil temperatures mean seedlings emerge more slowly, thus giving the maggots a longer time to feed. Later planting can help minimize the seedcorn maggot risk, as can removal of debris from rows and closing of the seed slot. Insecticidal seed treatments are effective in controlling seedcorn maggots under most circumstances. For more information on the seedcorn maggot, see Early Season Insect Pests of Corn.
Some solutions to both seedcorn maggot and black cutworm in corn stands in which soil conservation is a high priority include knowing the life cycles of insects that pose increased threats and increasing scouting efforts in at-risk fields, particularly during stand establishment.
How Do You Monitor Alfalfa Weevil?
Alfalfa weevil can be a problem for established alfalfa fields prior to and shortly after first harvest. To avoid unnecessary losses associated with injury from this insect pest begin monitoring fields in mid to late April when growing degree days have reached about 280 GDD (base 48F). The monitoring process is very straight forward. Look for signs of weevil feeding as holes in leaves and leaf buds and assessing the percentage of leaves affected. Here's how:
Record the percentage of alfalfa stems that show the "shot hole" feeding damage in the top 3 inches of the canopy.
Alfalfa Weevil Tip Larval Feeding
Before the first cutting, if 40% of the stem tips show feeding damage, you are at the "action threshold". The good thing is that alfalfa weevil can generally be controlled by harvesting. If you reach an action threshold within a week of your normal 1st cutting date, early harvesting will help avoid economic, yield, and forage quality losses. Alfalfa weevils only have one generation per year and are typically not a problem after first harvest. Occasionally, weevil can damage alfalfa re-growth after harvest. This damage may be more evident in the windrow areas, and can be more noticeable under cool or droughty weather conditions. If you find that 50 percent of the new growth is damaged, with many small larvae present, a chemical control may be warranted. For more information on alfalfa weevil checkout our online publication: IPM for Alfalfa Weevil
Practice Soybean IPM Before Planting
Cool weather is hanging on in many areas of NY, but soybean planting has begun. Let’s review some of the pre-season insect and disease management considerations for soybeans. Fungicide treatment on soybean seed is generally not needed in NY when high quality seed with a germination rate of at least 85% is planted. Check your field records from the last time soybeans were in your planned fields - was there damping off (rotting seedlings), or Phytophthora root rot? If yes, fungicide seed treatment may be warranted. Plus, the earlier the planting (and the cooler and wetter the soil), the more likely the field is to benefit from a fungicide seed treatment.
Insecticide seed treatments may help control seed corn maggot and wireworms in soybeans, but because soybeans readily compensate for gaps in the rows, a small stand loss from these insects is not usually a concern. Insecticide seed treatments on soybean have not been shown to adequately control soybean aphid (SBA) in university research trials across soybean-growing regions of the
Scouting for early season disease and insect pests should begin as soon as soybean plants start emerging. We will provide more information about specific seedling disease and insect pests, and how to scout for these pests, in upcoming issues of this report.
With the increase in interest in producing bio-fuel with oilseed crops, there have been a number of questions regarding canola pest management, so I am preparing 2 articles. The first one on Canola diseases appears in this week’s report. Next week we'll have a companion article on common insect pests of canola we might anticipate in our area. While there are several diseases of canola the two most important to consider in our area are: blackleg and Sclerotinia stem rot. Remember, what you do for other field crop diseases, like seed treatments and good sound crop management, can help the plant stay healthy and prevent infection to a large degree.
Blackleg one of the most serious fungal diseases of canola in
The disease over winters and survives on residue from previous crops of canola. The fungus can also infect seed and be transmitted to new fields at planting. The spores of blackleg can be transmitted during the growing season by splashing rain or airborne spore on wind currents.
Management of Blackleg
Sclerotinia Stem Rot (White Mold)
White mold infects several crops including canola, alfalfa, soybeans, peas, chickpeas (garbanzos), lentils, sunflowers, sweet-clovers, and many broad-leaf weeds. Warm-humid and wet weather can cause the proliferation of infection to canola. The first symptoms of white mold are soft-watery lesions on leaves and stems. As the infection continues the lesions become grey to white and sometimes have a concentric ring pattern. The lower stems appear bleached and the tissues on the stem start to shred as the infection progresses. When the stem dies the tops of the plants appear prematurely ripened. When white mold infects canola at flowering the plant will produce very little to no seed. The disease becomes more pronounced with dense stands of canola, thus, a dense canopy can create high humidity that is favorable for white mold. When cutting open an infected stem will you will discover a cottony white mold. Within the cottony mass of mold you will also find hard black fungal structures, known as sclerotia (fungal "seeds") that look much like a peppercorn. The sclerotia are round, elongate or irregular in shape and range from ½ to ¾ of an inch. The most important time to scout for white mold in canola is just before flowering. To view symptoms of this disease please view Sclerotinia Stem Rot of Canola. Sclerotinia can survive in the soil and crop residue for several years. This disease can also infect seed and be introduced to a new field at planting.
Management of White Mold
Fungicides: It is an important practice to make sure the seed is treated with a fungicide.
Growing Degree Days for NYS
March 1 - May 13, 2007
*Indicates missing data
Growing degree Days for peak (50%) Occurrence of Alfalfa Weevil growth stage:
(Note: for alfalfa weevil predictions use Base Temp of 48F)
PESTICIDE EMERGENCY NUMBERS
New Publication Available
Buckwheat Cover Crop Handbook. Thomas Bjorkman, Robin Bellinder, Russ Hahn, and Joseph W. Shail, Jr (authors)
Buckwheat has been used to suppress weeds on Northeastern farms for 400 years. The practice had been used here for a century and a half by the time George Washington and Thomas Jefferson corresponded with each other about how well it worked on their farms. It still works.
On modern farms we have different tools, a different market, and different economic constraints; so buckwheat will be useful in different situations. In this brochure we describe situations where buckwheat has high value on 21st century farms because it controls weeds economically and in a way that adds significantly to the other weed control practices that are available.
This handbook is based on extensive grower surveys, gathering knowledge held by successful growers, material printed in obscure old extension and farm publications, as well as original research to answer new questions. The instructions have been tested by cooperating farmers to make sure they work.
To keep the handbook short, the authors have included only what growers need to do and why. The substantial research and testing that went into determining the right procedures is not included, but there is a lot of experience behind every recommendation.
The handbook is designed to fit in a pocket, with a cover that can handle life in the barn or the truck, because that is where users will want the information that's in it. The specific instructions for the four main scenarios are also provided on water-resistant cards that can be kept in a place that's convenient for checking the next step during the season.
Electronic versions (PDF and HTML) of the brochure are available at the Cover Crop Guide.
Heavy-duty print copies are available at the Station online bookstore for $2.50. More information on both cover crops and buckwheat production at Cover Crops for Vegetable Growers, and Extension Information for Buckwheat Growers.
Small Grains Field Day
*June 5, 2008
Robert B. Musgrave Research Farm
Seed Growers Field Day
*Tuesday July 8
NYSIP Foundation Seed Barn
Weed Science Field Days
*Wednesday, July 9, 2008
Valatie Research Farm
9:30 am - Noon
*Wednesday, July 16, 2008
Robert B. Musgrave Research Farm
1:30 pm - 5 pm
Wednesday, July 23, 2008
Robert B. Musgrave Research Farm
Julie Dennis: IPM Area Educator, Livestock and Field Crops,
Keith Waldron: NYS Livestock and Field Crops IPM Coordinator