Tag Archives: soybean diseases

Fall Tillage Impacts Soybean Diseases

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To till or not to till? That’s been one of the most frequently asked questions this fall as many farmers finished harvest 30 days ahead of last year and weather conditions allowed them to work the ground.

Fall tillage practices impact Soybean White Mold and Sudden Death Syndrome, says Iowa State University Plant Pathologist X.B. Yang. The effects of fall tillage are completely opposite: no-till can decrease the risk of White Mold while SDS is usually more severe in no-till fields.

SDS is more severe in no-till situations because soil temperatures remain cooler and wetter, according to a recent Wallaces Farmer article. No-till fields have a lower risk of White Mold, however, due to the placement or distribution of sclerotia. 

To read this article in its entirety, click here.

Widespread SDS has many asking, “What do I do?”

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In last week’s crop report, we highlighted the fact that SDS has been widespread in Iowa and surrounding states. One reason we’re seeing widespread SDS this year is because fields have experienced the perfect storm: soils that were compacted last fall due to a late and wet harvest were also wet and cool during the 2010 planting season. As a result, ideal conditions were created for the soil-borne fungus that causes SDS.

Farmers throughout Latham service areas, including Iowa, Minnesota, Wisconsin, Nebraska, Missouri and South Dakota, have been asking repeatedly, “What should I do?”

Although there isn’t anything you can do right now to minimize the severity of damage from SDS this season, there are multiple management practices you can employ to help ensure SDS doesn’t strike again in the future. Ways to avoid future SDS damage include:

  1. Crop rotation – Make sure you don’t plant beans-on-beans in fields that have been hit with SDS. Note fields where SDS is especially prevalent. Crop notes will help you plant a soybean brand with high SDS tolerance in those areas the next time you plant soybeans.
  2. Tillage – No-till practices allow soil to remain cooler and wetter longer, which can increase the severity of SDS. Tilling helps change soil conditions to be more adverse to SDS.
  3. Planting Date – Planting at a later date can help reduce the risk of SDS, as well.
  4. And Variety Selection – Variety selection is incredibly important. Choose soybeans brands that have high SDS tolerance. Latham® brands that have done very well in SDS-affected soils include the following:
    1. L2085R
    2. L2767R2
    3. L2987L
    4. L2648R2
    5. L2875R
    6. L3268R2

We will follow up with additional blogs on SDS this week. Please feel free to ask any questions you may have about your own fields. Are you seeing SDS in your fields? If so, to what degree?

How to Check Fields for Soybean Cyst Nematode

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Soybean cyst nematode (SCN) is a small, plant-parasitic roundworm that attacks the roots of soybeans. SCN is widespread throughout Iowa and surrounding states, and can cause as much as 40% yield loss without symptoms appearing on the soybean plants.

Symptoms to Watch For

A recent Wallaces Farmer article highlighted what symptoms to watch for when checking for SCN in your field. Symptoms are usually not apparent when temperatures are moderate and rainfall is adequate to excessive in the growing season. Symptoms generally begin to appear in mid-July and last through the growing season, and include stunting of plants, yellowing of foliage (not just leaf margins or areas between leaf veins) and mid-day wilting.

Dig, Dig, Dig

The only way to check for SCN is to dig roots, gently remove soil from the roots, and look for the egg-filled, round, white SCN females on the roots (see image). Females are about the size of the head of a straight pin or a period at the end of a sentence in a magazine – for most people – females can be seen with the unaided eye. SCN females should be apparent on infected roots through August.

While this is an effective way to identify SCN, it’s also an effective way to see which soybean varieties are controlling nematode reproduction in fields known to be infested. If a soybean variety is effectively controlling the nematode, there should be only 10-20 SCN females present on the roots.

Click here for the full article.

Photo courtesy of Iowa State University Extension.