Yellowing leaves in soybean plants can often be mistaken for a potassium deficiency, but the underlying issue may be more complex. Potassium deficiency typically manifests as yellowing in the middle or upper canopy, but other factors should be considered to accurately diagnose and treat the problem.
According to Matt Montgomery, a Pioneer Field Agronomist, yellow leaf symptoms alone do not always lead to the true cause. Therefore, a comprehensive checklist must be followed to eliminate potential causes and identify the appropriate course of action.
Aside from potassium deficiency, yellowing leaves can be attributed to herbicide damage, fungal diseases, or pest infestation. If these factors are ruled out, the focus should shift underground. Soybean cyst nematodes (SCN), which are microscopic, worm-like parasites, can significantly reduce yields without obvious symptoms. However, high populations of SCN can induce yellowing leaves.
Montgomery explains that SCN females primarily feed on the root material of plants, gradually depleting water, photosynthates, and nutrients. Above-ground symptoms are usually absent unless the soil is stressed, and SCN levels are high in the field.
Effectively managing SCN entails two approaches: preventing infestation in fields and reducing nematode populations in infested areas.
The initial step is to prevent field infestation by implementing crop rotation with resistant soybean varieties. If infestation has already occurred, early identification is crucial for developing a management plan to ensure profitable soybean production. Halting or slowing the spread of SCN can prevent future losses.
To create a successful SCN management plan, the SCN Coalition recommends the following strategies:
- Conduct field tests to determine nematode population numbers.
- Implement crop rotation with resistant soybean varieties.
- Rotate to non-host crops.
- Consider utilizing nematode protectant seed treatments.
By understanding the various causes of yellowing leaves in soybeans and implementing effective management strategies, farmers can safeguard their crops and optimize yields for years to come.
Photo Credit: gettyimages-gilaxia
Categories: South Dakota, Crops, Soybeans