Walking Your Fields® Newsletter - South Delta and Coastal Plains
Sample for Nematodes Before It Is Too Late
Plant nematodes are one of the most numerous organisms in the soil. They are microscopic animals that can damage plants, and since most are not visible to the naked eye it is hard to associate these pests with crop damage. Crop damage can be severe, causing more than 30% yield loss or even seedling death. Fall is an excellent time to collect nematode samples. This needs to be done at least every 2 years, especially if you are not in a good rotation. This will allow you to monitor nematode species and populations before they build to damaging levels. Collecting samples for nematodes can NOT be done in the same manner as regular soil tests.
- Nematodes are best captured in soil samples before any fall tillage is done and low yielding areas of the field can be targeted. Samples do not need to be random; target the problem area. Nematodes are usually clustered in irregular areas of the field.
- Do not sample dead plants. Instead target live plant areas that have a range of symptoms but are lower yielding. Dead plants have roots that have deteriorated and the food source is gone.
- Capture root tissue if possible, so samples will need to be pulled from 4-12 inches deep in the root zone near crop rows.
- Take care to handle samples as perishable and get them to a lab quickly.
- Keep track of field history and early crop growth and health.
- I always say that nematode sampling is much like fishing - just because you don’t catch a fish today doesn’t mean there are not fish in the lake. The absence of nematodes in a soil sample doesn’t rule out this pest as a cause of a problem, you may just need to sample in a different way at a different time, depth or area of the field.
- Sting, stubby root and root-knot are the most damaging to corn.
- Cyst, root-knot and reniform are among the most damaging to soybeans.
What Causes Green Stem in Soybeans?
The industry has selected high yielding soybean varieties that produce and store photosynthates in plant vegetation until the developing reproductive structures remobilize the sugars, starch and nitrogen from stems and/or leaves to the growing pods and seeds. If pod number is significantly reduced at R6, then stem and leaf maturity will be delayed. Drought conditions and insect pests in areas of fields resulted in some pod abortion during August and early September, especially the full season varieties or later planted fields. We could expect to see some green stem in those areas of the field that are more drought prone.Research has found that:
- Pod abortion often only slightly delays pod maturity - averaging 2.5 days for the 25% depodding treatment and 6 days for the 50% depodding treatment.
- Pod abortion can significantly delay stem maturity - by 1 to 6 weeks.
So, in those cases where low pod numbers have delayed stem and leaf maturity, growers must be diligent in scouting fields because the pods may be mature and the soybeans dry enough for harvest. Be prepared to use harvest aids.
Reducing Yield Loss from Shattering in Soybeans
Shattering can be influenced by genetics as well as the environment and management of soybeans. Timely harvest is essential to reduce losses.
- Pioneer® brand soybean varieties are rated for resistance to shattering.
- Yield losses can be roughly calculated by counting the seeds on the ground - every 4 beans per square foot is equal to approximately 1 bushel per acre.
- Drought during pod development can increase shatter. Spider mites can make it worse.
- High temperatures can increase shatter.
- Physical insect damage to the pods from beetles or grass hoppers can increase shatter.
- Delayed harvest and a repeated wetting and drying cycle that occurs from nightly dew fall and subsequent drying during the day can cause pods to split. Seed moisture below 11% can increase risk significantly.
- Proper combine speed and slowing ground speed can help reduce gathering losses. Sharp knifes, proper reel speed relative to ground speed and proper reel height are all adjustment factors that affect losses.
Maintain Focus on Weed Control
As you make seed selections for 2018, be sure to include plans for effective weed control next season. Identify problem fields and determine what traits, herbicides and cultural practices will help manage weed competition to protect the crop's genetic potential for yield. Good winter annual weed management is the first step in an effective weed control program for 2018.
Remember the Rules for Herbicide Management
Scout late-season and harvested fields for resistant weed populations and stick to the basics to keep resistance under control: Start clean with a burndown treatment or tillage plus a preemergence herbicide application. Use cultivation and crop rotation where appropriate and follow with integrated weed management, including multiple modes of action and full herbicide rates that target the toughest weeds.
THANK YOU FOR READING!
Your DuPont Pioneer Southern Agronomy Team
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Encirca® services provides estimates and management suggestions based on statistical and agronomic models. Encirca services is not a substitute for sound field monitoring and management practices. Individual results may vary and are subject to a variety of factors, including weather, disease and pest pressure, soil type and management practices.
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