Weekly Field Crops Pest Report 2006

View From The Field

Julie Stavisky, NYS IPM

Ken Wise, NYS IPM

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Western NY and Finger Lakes Region

I observed a lone cereal leaf beetle adult in field visits early this week, but I did not yet see any eggs or larvae in winter wheat or spring grains. Mike Stanyard observed CLB eggs in oats in Wayne County

In alfalfa observations in Wyoming and Ontario counties, alfalfa weevil adults are present in very low numbers.  Pepperweed is starting to flower, and chickweed and purple deadnettle are abundant.

Because there will be TAg teams in several counties in WNY this year (See "TAg is Sweet 16" below for more information), we will be providing you with weekly scouting reports from many areas all summer long.  Stay tuned!

This week I have seen a few alfalfa weevil adults and 1st instar larvae at the Cornell University Research Farm in Valatie. I have also seen several different species of lady beetles this year. In a future issue I will prepare and article with photographs of how to identify these common lady beetles species. On Friday Anita Deming, Mike Davis and I will be having our 1st organic wheat TAg  meeting at he Cornell University Research Station in Willsboro in Essex County.

TAg is Sweet 16!

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The Tactical Agriculture Team Program (aka TAg) turned Sweet 16 in 2006. Since its initiation in 1990, CCE personnel have offered TAg in 30 Counties. Over 900 producers and other agribusiness personnel have participated in this program that own or manage 184,000 acres of field crops. For more information see NYS IPM Program's TAg website.

This summer TAg team programs will again be offered by a number of CCE educators bringing IPM and ICM education to a variety of field crop producers. In addition to directly helping local participants, field observations from TAg programs will be incorporated into the Weekly Pest Report.

TAg Programs will be active in:

Seed Decay and Seedling Diseases of Corn

Julie Stavisky, NYS IPM

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Seed Decay
Seed decay is caused by a number of soil-inhabiting fungi such as Pythium, Fusarium, Diplodia, Rhizoctonia and Penicillium. These fungi can infect seed before it germinates, causing mortality. Seeds infected with decay fungi are discolored and soft. Many times fungal material may grow on the seed. If you are digging around in the soil to investigate those gaps in the row, a seed that has rotted may be completely decomposed and therefore cannot be found.  This can make tracking down the culprit a little difficult!

Seedling Blight
Sometimes the seed may germinate and grow but will die as the plant emerges from the soil. Seeding blights are caused by many of the same fungi that cause seed decay. Seedling blight symptoms include discolored seedling coleoptiles and roots. Seedlings may have a wet, rotted appearance before they reach the soil surface. Above ground symptoms of blight may include seedlings that turn yellow, wilt and die.

Factors that contribute to both seed decay and seedling blights may include cold, wet soils.  These unfavorable conditions can lead to slow emergence and slow growth of seedlings.  Plant or seed injury from fertilizer burn, incorrect herbicide application, or soil crusting can add to plant stress at the vulnerable seedling stage.  Fortunately, planting high quality corn seed is common practice, and fungicide seed treatments are a normal part of the spring routine for many producers.  These practices prevent many outbreaks of seed decay and seedling blight.

See our brochure on early season disease management for more information.

Blind Cultivation: An Alternative Early Season Weed Control in Corn

Ken Wise, NYS IPM

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Cultivation has been used for thousands of years to reduce weed competition with row crops. It is only recently, that we have had herbicides to control weeds. With concerns for the environment and costs of herbicides, cultivation is slowly starting to be used again by field crop producers. All organic corn producers use cultivation. Interest in revisiting this weed management practice is also increasing among conventional corn producers in New York State.

Timing is Everything. Timing early season weed control is always a very important aspect of maintaining good corn yields. Weeds compete for limited resources. If weed control is delayed until after the V4 stage of corn growth yields start to drop dramatically. The question by most field crop producers is “how do you control early season weeds with cultivation?”.

One method that is being used is “blind Cultivation” also known as “broadcast weed cultivation”. No, this isn’t done while closing your eyes while driving the tractor… Blind cultivation uses certain kinds of cultivators to disrupt the top 1/2 to 1 inch of soil, uprooting and exposing the newly sprouting weed seedlings (before the emerge?) to desiccation while the seedling are still very tiny. Scouting fields is a requirement to know when weeds are in the “white root stage.” The stage where the seed begins to sprout and the seedling hypocotyl is elongating. Blind cultivation works best when it is hot and the sun is hitting the surface of the field. The goal of this method is to kill weeds when they are they most sensitive to disturbance. Normally a blind cultivation occurs a week after planting and again once the corn is 2 to 3 inches tall depending on the cultivator being used.

Planning is essential if you want to use blind-cultivation as a means to control annual weeds. One aspect to consider is what kind of cultivation tool will best fit a farming situation? Rotary hoe, flex-tine weeder, and spike tooth harrows are some of the mechanical weeders being used to control early season annual weeds in field corn.

The rotary hoe is a common mechanical weed control tool used in a blind cultivation system. This is a high speed tool to pluck tiny weeds from the soil. Spider wheels with curved teeth rotate around a strait staff. Alternate wheels are offset for maximum soil contact. A rotary hoe can be used for weed control pre-emergent or post-emergent. The fingers on the hoe are very aggressive and can damage the emerged corn if not preformed correctly. This weeder is very effective at up-rooting and killing weeds. The hoe can penetrate the soil 1 to 2 inches deep without damaging the crop. Increase your seeding rate by 2 percent/weeding pass to compensate for possible damage. In addition to its role in weed management, a rotary hoe is very effective at breaking up and aerating crusted soil conditions. If a rotary hoe is going to be used on post-emergent corn only cultivate up to about 6 to 7 inches tall. Do not expect to kill green weeds because their root systems have become too deep.  Soil with stones can damage and get stuck between the rotary hoe fingers.

A flex-tine weeder is becoming a common cultivator for early season broadcast weed control. This tool has multiple round or angle iron framing members that hold round or flat spring steel teeth that run about ½ inch deep into the soil, vibrating and moving around obstructions. This tool can be used pre-emergence or post-emergence when annual weeds are in the white root stage. Do not let weeds green-up because the root system will become too deep for the tines to up-root them. A flex-tine weeder can be used on corn up to 7 inches tall without much crop damage. While the rotary hoe is best for breaking up soil crusting the flex-tine weeder also does a good job at this if the tines are at a 45 to 80 degree angle. One advantage with using a flex-tine weeder is that a stony field does little or no damage to the tines. One disadvantage is the aggressive action can damage emerged corn if you are not careful. As you increase the angle of the flex-tines the more aggressive the soil disturbance and possible damage to the corn crop.

The spike-tooth harrow has been used for blind cultivation and can be effective. The harrow has horizontal bars that hold square metal rods about 8 inches long, turned at a 45 degree angle so that so that the corner runs forward. Make sure that the weeds are in the white root stage. While this works best as a pre-emergence control, it can be used post-emergence up to 7 inch corn.  Weeds are most effectively controlled when the weather is sunny and warm. Stones can be a problem for a spike-tooth harrow. Rocks can damage the teeth and/or get caught between teeth and can rip out rows of corn if not watched carefully.

By using blind cultivation a producer can reduce or eliminate the use of herbicides on the farm. If blind cultivation is combined with row cultivation later in the growing season the use of herbicides may not be needed. By using blind cultivation early in the season and just a post-application of herbicides later in the season a producer can reduce the use of herbicides on the farm.

Timothy Stands Looking a Little Less than Perfect?

Keith Waldron, NYS IPM

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Clear stand of timothy? Stunted areas within field? Drought stress symptoms when soil moisture appears adequate? Top 2-6 inches of leaf tips chocolate brown in color? Some leaf tip flagging or distortion?

Could be a sign that field has Cereal Rust Mites (CRM) aka Abacarus hystrix (Nalepa). Symptoms of CRM damage include: retarded growth, stunting, and plant discoloration. Injured plants appear to be drought stressed even when adequate moisture is available for plant growth. As with most grasses, the edges of timothy leaves roll together when the plant is under moisture stress.

In recent years, CRM has been a problem in Pennsylvania, Delaware and Maryland. In NY, Mike Stanyard has found CRM infestations causing potential problems for some timothy hay producers in the Finger Lakes region. A very informal survey several years ago found adult rust mites present in timothy in various places across NY, although economic impacts were not observed or measured.

Severe mite infestations can have two possible negative impacts. Feeding injury causes substantial yield losses and reduces hay quality because of the brown discoloration. Horse producers are reluctant to buy hay that is not the normal color of quality timothy.

This mite is miniscule in size making it not only hard to see, but equally hard to study. How would you know it was there? Compare field observations against the symptoms described above. Pick a few choice leaves showing the brown / flagging leaf tip symptoms, use your most powerful hand lens, look for presence of the tiny mites between leaf veins. (From the fact sheet cited below) Adult rust mites are very small (<1mm). They are spindle-shaped, with four legs and may be white, yellow or orange. You will need a 10 to 20X hand-lens to see them. Evidence of their presence on the plant is off-colored foliage and leaf or bud abnormalities. Large mite populations often produce many elongate, white shed skins. The immature stages are similar to the adult, but smaller. Immatures begin hatching in March, with the peak adult populations being reached peaking in April. Damage is most evident in April and May.

Management? Little is known at this time. The best information comes from PA, DE and MD.

Pennsylvania guidelines: Economic Thresholds - There are no established economic thresholds for this pest. Treatment is recommended, however, in fields with a previous history of cereal rust mites and/or when 25% of the plant tillers exhibit curled tips on the new leaf blades within several weeks following green-up. They continue stating… “Research is underway to develop better monitoring plans and economic Threshold”. For more information see the Cereal Rust Fact Sheet from Penn State.

Note: No insecticide/miticides are registered for use in NY to control CRM.

Soybean Rust Updates

Keith Waldron-NYS IPM

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From: New York State Soybean Rust Information Center

At this early point in the growing season, the potential for early and severe soybean rust in the northern states in 2006 is unclear.  The 2006 North American epidemic is starting from over-wintered rust on kudzu in a somewhat broader and more northerly area than in spring 2006, yet early pockets of rust from Florida to Alabama are scattered and of low severity.  Also, much of the infested area of the Southeast has experienced hot and very dry conditions in recent weeks.  To date, in 2006, soybean rust has been reported on kudzu in five counties in Alabama, 11 counties in Florida, and four counties in Georgia. While soybean rust was found in a mature field of soybean in far southern Texas in February, the infected field has since been destroyed and no new rust has been found in Texas.  Scouting on kudzu patches continues throughout the southeastern U.S. expanding northward to southern Illinois, and westward to Texas. Many of the soybean sentinel plots have been planted in most southern and some mid-western states. Soybeans in sentinel plots have emerged as far north as central Illinois.  We are finalizing plans for approximately 20 sentinel soybean plots in New York to be scouted in cooperation with soybean producers and Cornell Cooperative Extension Educators. Last updated (May 1, 2006)

National Map Commentary, see USDA Soybean Rust Website (last update: 04/24/06)

Birds in Corn

Keith Waldron-NYS IPM

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Last year there was a lot of discussion on what to do about birds (crows, turkeys, geese) in field corn. Nothing has changed from last years recommendations. To review: Propane cannons may provide some relief, however our feathered friends can adapt to the sound and one should consider community relations when installing a source of regular “Ka-Booms”. Other suggestions include paying close attention to planter settings for depth and seed slot closure, planting at a higher population on fields where bird feeding is anticipated, setting out alternative or decoy foods for birds – such as moistened corn seed.

Alfalfa Weevil and Growing Degree Days in NYS

Ken Wise and Keith Waldron-NYS IPM

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Growing degree Days for peak (50%) Occurrence of Alfalfa Weevil growth stage:

Accumulated Growing Degree Days for March 1 to May 2

Clipboard Checklist

Keith Waldron-NYS IPM

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General:

* Emergency contact information (“911”, local hospital, Chem. Spill emergency contact, other?) posted in central posting area

* Review EPA Worker Protection Standard training and posting compliance needs

* Walk fields to check tile flow, check and clear drainage outlets.

* Maintain crop records by field, including variety, planting date, pesticides used, nutrient inputs including manure, etc.

* Watch for early season weeds

Corn:

* Finish corn planting by May 15, if soil conditions allow

* Use corn insecticide seed treatment in the planter box

* Monitor for weeds, note presence of “who”, “how many” and “where”

* Adjust post emergence weed control actions

* Determine corn plant populations, make notes on germination problems

Small Grains:

* Monitor winter grains for crop stage, insect and disease problems

      - assess crop for adequate stand and plant vigor

Alfalfa & Hay:

* Monitor alfalfa seedings for weeds, insects & diseases.

* Check established alfalfa stands for over wintering injury, frost heaving, alfalfa weevil, weed and disease problems.

* Timothy stands: check fields for symptoms of cereal rust mite

Equipment:

* Note any repairs needed for corn planter, seeding equipment, alfalfa harvesting equipment, and tillage implements as they are cleaned and lubricated.

* Service corn planter as needed.

* Calibrate manure spreaders - maintain records on amount spread per field

Contact Information

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Julie Stavisky: IPM Area Educator, Livestock and Field Crops, Western NY
Phone: (315) 331-8415
Fax: (315) 331-8411
Email: js38@cornell.edu

Keith Waldron: NYS Livestock and Field Crops IPM Coordinator
Phone: (315) 787 - 2432
Fax: (315) 787-2360
Email: jkw5@cornell.edu

Ken Wise: Eastern NYS IPM Area Educator: Field Crops and Livestock
Phone: (518) 434-1690
Fax: (518) 426-3316
Email: klw24@cornell.edu