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Weekly Field Crops Pest Report 2006

September 8, 2006 Volume 5 Number 19

1. View from the Field

2. Harvesting Soybeans Soon? Think Stored Grain Pests!

3. Fall IPM in Alfalfa

4. Watch for Signs and Symptoms of Soybean Cyst Nematode

5. NYS Growing Degree Days

6. Clipboard Checklist

7. Contact Information

View From The Field

Eastern NYS
Ken Wise, NYS IPM

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Next week will be the last issue of the NYS IPM Weekly Field Crops Pest Report for 2006. We plan to continue this publication next growing season. We will compile a web-linked index of all the issues and articles we published this year. We will also follow-up with a survey on how effective this publication is to your extension programming in the next few weeks.

This week in the soybean field I monitor in Columbia County I discovered large areas and rows of yellowing plants. After a while of trying to figure out what the problem was I pulled a yellow plant out of the ground. It had no nodules on the roots while the green plants had many. Most likely the inoculum must have been miss-applied to the seed and some plants did not form nodules.

Yellowing Soybean Plant Roots

Green and Healthy Soybean Plant Roots

Yellowing and Green Soybean Plant Appearance

Soybean bean aphid populations remain low, ranging from 30 to 180 SBA’s per plant sampled. I am still seeing the white dwarf form of soybean aphids on most of the plants. I did not see any winged soybean aphids.

This week I did not find a single potato leafhopper in any alfalfa fields sampled at the Cornell Research Farm in Valatie. In late summer and early fall, potato leafhoppers migrate back to the southern United States. Potato leafhoppers over-winter on pines and numerous other host plants in the southern and southeastern United States.

Harvesting Soybeans Soon? Think Stored Grain Pests!

Ken Wise, NYS IPM

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It is time to start CLEANING your grain bins. Sanitation is the key to keeping insect pests out of your stored grains. Soybean harvest is not as far off as you may think so knowing what you need to do is important. The following is a step by step method for IPM in stored grain:

1. Clean grain handing equipment (augers, combines, wagons, scoops, and trucks).

2.Clean inside the grain bin (remember to clean under the false floor). Mice, moths, weevils and much more can survive under the false floor.

3. Clean around the outside of the grain bin. Remove all weeds, spilled grain and debris 6 to 10 feet from around the grain bin. This will remove all habitats that can support a grain bin pest problem.

4.Seal all cracks and crevices. Cracks are prime locations for insects to enter grain bins.

5. Cover fans when they are not being used. Insects can enter the grain bin this way also.

6. Use a registered sanitizing insecticide spray in and around the structure after cleaning.

7.Never store new grain with old grain.

8. Dry the grain bin before adding new grain. Insect pests need moisture to survive.

9.Level the surface after filling the grain bin. Moisture accumulates in a grain peak. Microbial activity in the wet area will heat up and attract secondary insect pests.

10. Do not fill grain bin all the way to the top. Leave a few feet for aeration.

11. Aerate the grain to at least the ambient temperature. The hotter the grain gets the faster insect pests can develop. Stored grain insect pests development slows when the temperature falls below 500 F.

12. Monitor grain for insect pests every 20 days from spring till fall and every 30 days in the winter.

13. If you discover an infestation of insect pests you may consider an insecticide application. Select a NYS registered product for your stored grain. READ THE LABEL.

14. Keep areas around grain bins mowed to limit rodent hiding places.

Common Stored Grain Insect Pests:

  • Granary weevil

  • Saw tooth grain beetle

  • Red flower beetle

  • Larger cabinet beetle

  • Lesser grain borer

  • Rice weevil

  • Indian-meal moth

  • Flat grain beetle

  • Angoumois grain moth

  • Confused flower beetle

(See: IPM in Kentucky Farm Stored Grain, IPM Tactics for On-Farm Stored Grain, and Improve Stored Grain Through IPM

Fall IPM in Alfalfa

Ken Wise, NYS IPM Keith Waldron, NYS IPM

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Fall stand counts are an indication of the health of your alfalfa crop. There are a number of pests and crop management issues that can reduce a stand count in alfalfa. The following are guidelines for stand counts in NYS:

 

Crowns per square foot

Harvest Year

Optimum Stand

Adequate Stand

New Spring Seeding

25-40

12-20

1st hay year

12-20

6-10

2nd hay year

8-12

4-6

3rd and older

4-8

2-5

Fall scouting before the first hard frost can also reveal pest problems. If you find yellow to brown plants it may indicate several different disease problems. These could range from a wide variety of disease problems including, Verticillum wilt, leaf spots, Fusarium wilt, anthracnose and more. An inspection of the root system can also indicate disease problems. Yellow, reddish-brown to black discolored or damaged roots may indicate disease problems such as Phytopthora root rot or Verticillium wilt. Premature senescence of alfalfa stands may indicate stress damage by Alfalfa Snout Beetle larvae from those counties with confirmed infestations.

Watch for symptoms and signs of Soybean Cyst Nematode

Keith Waldron, NYS IPM

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This summer, thanks to the efforts of our many Soybean rust/aphid sentinel plot monitoring network volunteers, we have accumulated a large amount of statewide information regarding soybean pest occurrence. This information has documented the absence of soybean rust and a general sub-economic population of soybean aphids in NY this season. In addition to those two key soybean pests field observers  have reported the presence of "White Dwarf" soybean aphid forms, white mold, and the first documented NY occurrence of two soybean diseases sudden death syndrome (Fusarium solani f. sp. glyines) and brown stem rot (Phialophora gregata f.sp. sojae). This information will help to improve the data upon which to base management recommendations and guide future research efforts.

The potential threat of soybean rust this season has passed and soybean aphids should soon begin developing their winged forms signaling their movement out of fields and to their winter hosts. Soybean monitoring efforts will continue until first frost or soybean dry down. This time of year soybean producers should be on the lookout for field symptoms which can indicate the presence of soybean cyst nematodes (SCN). Fortunately, this pest has not been reported in NY. However, our environmental conditions are similar to Ohio, Pennsylvania and Ontario, Canada where SCN has been confirmed in the last two decades.

The soybean cyst nematode (SCN), Heterodera glycines, is a parasitic eelworm that damages root systems, interferes with uptake of water and nutrients, causes stunting, reduced stand populations, crop yield and can predispose plants to root infecting diseases. Symptoms of SCN damage can be mistaken for other crop production problems such as stand establishment issues, seedling diseases/blights, nutrient deficiencies, and soil compaction.

Nematode populations build up over the summer and signs of their impact can be seen in field symptoms in the fall. Symptoms of SCN injury can be mistaken for damage from compaction, iron deficiency chlorosis and other nutrient deficiencies, drought stress, herbicide injury, or other plant diseases.

A description of SCN and it's injury to soybeans can be found in the IOWA STATE UNIVERSITY factsheet: "Soybean Cyst Nematode" prepared by Greg Tylka, extension plant nematologist.

The following information is taken from that reference.

"The first obvious symptom of SCN injury to soybeans is the appearance in the field of circular- or oval-shaped areas of stunted, yellowed, less vigorous plants. These infested areas will vary in their size, often showing a sharp dividing line at the edges between stunted and apparently healthy plants.

In areas with high pH soils, the yellowing of soybeans due to SCN often is confused with iron deficiency chlorosis. However, there are differences between symptoms of the two problems. Iron deficiency chlorosis symptoms usually appear in early June, whereas yellowing due to SCN will more likely occur in July and August. The yellowing caused by iron deficiency chlorosis typically affects the areas between the veins of the upper leaves. Yellowing due to SCN usually starts at the edges of the leaves, and can affect leaves on the entire plant. Iron deficiency chlorosis and SCN may occur in the same field and even on the same plant.

An area of SCN damage often will appear elongated in the direction of tillage operations. Most severe damage is often in the center of the area, with damage decreasing towards the margins. Such areas frequently develop near a field gate, entrance, wherever equipment enters a field, or near fences where wind-blown soil may accumulate.

The above-ground symptoms of SCN damage can range from nonexistent to severe depending on the age and vigor of the soybean plants, SCN numbers, soil fertility, moisture levels, and other environmental conditions. Injury usually is more severe in light, sandy soils, but it also occurs in heavier soils.

One cannot rely upon above-ground symptoms for identification of SCN infestations. If soybean yields in any field have decreased for no apparent reason, more thorough examination of plants for below-ground symptoms and a soil analysis for SCN are needed.

Below-ground Symptoms

Roots infected with SCN are dwarfed or stunted. SCN can decrease the number of nitrogen-fixing nodules on the roots. SCN infections also may make the roots more susceptible to attacks by other soil-borne plant pathogens. Often it is difficult to recognize if roots are stunted and have fewer nodules unless they are compared to uninfected soybean plants.

The only unique symptom of SCN infection is the presence of adult female nematodes and cysts on the soybean roots. These structures, which appear as tiny, lemon-shaped objects on the roots, are white initially, but turn yellow and then tan to brown as they mature. They can be seen with the unaided eye, although observation with a magnifying glass is easier. Roots must be carefully removed from the soil for examination or the cysts may be dislodged. Observation of adult females and cysts on the roots of soybean plants is the only accurate way to diagnose SCN infestation in the field."

NY Soybean Cyst Nematode Survey 2006

A limited soil survey of 19 soybean sentinel plots for soybean cyst nematode is being conducted in September through the Cornell Plant Diagnostic Clinic.  We are interesting in supplementing this survey with soil samples from other soybean fields where there is visual evidence of SCN-induced symptoms or where characteristic cysts (egg sacks) have been found on soybean roots.

If you monitor a soybean field with symptoms similar to those described above and you suspect SCN injury please contact Gary Bergstrom (gcb3@cornell.edu),  Keith Waldron (jkw5@cornell.edu), or Mary McKellar (mem40@cornell.edu) for further information on sampling methods and sample submission.

New York State Soybean Rust Information Center

Growing Degree Days in NYS

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Accumulated Growing Degree Days for March 1 to August 2

Location

Base 50 F

Batavia

1661*

Chazy

1968

Clifton Park

2078*

Geneva

2023

Ithaca

1878

Prattsburg

1763*

Redhook

2606

*indicates missing data

Source: NEWA

Clipboard Checklist

Keith Waldron-NYS IPM

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General:

* Maintain crop records by field, including crop condition, inputs, observations, issues, concerns, etc.

* Check grain storage bins for temperature, moisture and air flow.

* Mow around storage bins, barn and farm facilities

Alfalfa & Hay:

* Monitor fields for weeds and diseases record information on type and location, note stand condition for future cropping / rotation decisions.

Small Grains:

* Check grain storage bins for temp, moisture, air flow, drying conditions.

* Prepare for planting winter wheat after Hessian Fly-free date.

Field Corn:

* Harvest corn silage at 65 to 68% moisture and high moisture shelled at 25 to 30% grain, and high moisture ground-ear at 30 to 35% moisture.

* Record corn silage yields by field and quality by storage facility

- take samples for forage analysis

* Take Soil Samples for fertility analysis

* Take Fall Weed Survey following harvest.

 Soybeans:

* Monitor for crop condition and growth stage, white mold, soybean aphids, natural enemies, foliar diseases, sudden death syndrome (Fusarium solani f. sp. glyines), brown stem rot (Phialophora gregata f.sp. sojae), soybean rust

Livestock:

* Continue manure management and release of biological control agents (parasitic wasps) for house fly and stable fly control in barns

* Monitor young stock for cattle lice and mange mites

* Check condition of pastures and animals on pastures

- Evaluate need for face fly and stable fly control measures, adjust

paddock rotation as needed.

- Evaluate need for face fly and stable fly control measures

Equipment:

* Provide annual maintenance to fertilizer and pesticide application equipment,

* Note any repairs to harvesting equipment as they are cleaned and lubricated.

* Prepare combines for corn, soybeans

* Sharpen chopper knives. Check shear clearances, protective shields

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