Crops

Soybean Production in Warmer, Drier Spring

Planting Risks

In wheat/soybean double-cropping systems, the wheat is typically harvested earlier, allowing early planting of soybeans.

The lack of soil moisture associated with warmer and drier spring planting conditions can delay emergence.

Vegetative growth under these conditions is also affected. The plants that emerge tend to be too small for sunlight interception.

Strategies

  • Under anticipated warmer and drier spring conditions, planting should occur earlier. Also, growers should consider using cover crops and conservation tillage to preserve soil moisture.
  • Irrigation, if available, is another important safeguard.
  • Row spacing of soybean plants should be reduced and irrigation increased. Growers should also select taller varieties.

Insect risks

Several insects typically migrate into soybean fields faster during drier spring conditions.

Under these conditions, growers should anticipate higher populations of grasshoppers. Grasshoppers lay their eggs in the soil; however, these eggs aren’t as likely to fall prey to disease as they are under wet conditions.

Stinkbug populations also tend to increase in warmer spring conditions. Conversely, colder weather suppresses southern green stinkbugs and red-banded stinkbugs, which are more significant pests in the Southeast.

Dry springs also promote the spread of three-cornered alfalfa hoppers, which are more likely to migrate onto soybeans as wild host plants dry out earlier.

Thrips are another problematic insect pest in warmer springs. Wet springtime weather, on the other hand, typically contributes to higher mortality rates of immature thrips.

Strategies

  • Under drier spring conditions, growers should be aware that these pests will likely move into fields from host plants much sooner than usual.
  • Scouting is an essential safeguard, though many of these pests are difficult to detect given the small size of the emerging soybean plants.
  • Insecticides can be simultaneously applied with herbicide treatments that are sprayed on small beans as part of an early season weed control regimen.

Disease risks

During warmer and drier springs, especially those preceded by warm, dry winters, growers should monitor for soybean rust. Rust is a fungal pathogen that can survive on kudzu leaves along the Gulf Coast during years when temperatures are consistently above normal for this region. During mild winters, it’s likely that soybean rust will build up on kudzu in the spring and could potentially move into soybean production areas later in the spring and summer.

Strategy

  • Growers should follow the spread of soybean rust through the IPM Pest Information Platform for Extension and Education at http://sbr.ipmpipe.org/cgi-bin/sbr/public.cgi or through soybean rust alerts provided by their state’s extension system.
  • Growers may need to apply fungicides earlier in the season based on increased risk from this disease. Failure to deal with this disease early could trigger an epidemic later in the season.

 

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