Control seed-borne diseases in wheat with fungicide seed treatments
Fungicide seed treatments are becoming an important part of wheat production in Kansas. In 2019, Fusarium is an important issue for many seed producers. The seed-borne Fusarium often reduces germination and seedling vigor, which frequently translates into poor stand establishment. If growers suspect a seed lot may be affected by Fusarium, they should plan to clean the seed to remove the most severely damaged kernels, apply a fungicide seed treatment, and check the germination to help ensure seed quality.
Figure 1. Fusarium head blight wheat. Photo by Erick DeWolf, K-State Research and Extension
Other benefits of seed treatments
Although Fusarium is the major problem in 2019, there are additional reasons to consider fungicide seed treatments. The paragraphs below highlight some of the potential benefits:
Fungicide seed treatments help keep seed-borne diseases such as smuts and bunts in check. Loose smut control requires a systemic fungicide like tebuconazole or difenoconazole. Common bunt, sometimes called, “stinking smut”, can be controlled very effectively with most commercial treatments. Some regions of the state have struggled with these diseases in recent years. If you are planning to keep seed that is known to have or been exposed to common bunt, it is critical to use a fungicide seed treatment to avoid problems in the future.
Seed production fields are a top priority for fungicide seed treatments. These fields have a high value and investments in seed treatments here help prevent the introduction and development of seed borne diseases on your farm. Due to the high value of the seed produced, even small yield increases can justify the use of seed treatments.
Seed treatments can aid stand establishment when planting wheat after soybean harvest, even on seed that has high test weight and good germination. Planting wheat late into cool, wet soils often delays emergence, and reduces the tillering capacity of wheat seedlings. This reduced tillering capacity diminishes the plants ability to compensate for stand loss and maintain yield potential.
Some fungicide seed treatments also suppress the fall development of foliar diseases. For example, treatments containing tebuconazole and difenoconazole provide some protection against fall infections of powdery mildew, leaf rust, and Stagonospora nodorum leaf blotch. A seed treatment will not prevent the disease from becoming reestablished in the spring, and foliar fungicide applications may still be required to protect yield potential of the crop.
Things to remember
As with most things in agriculture, producers must balance the possible benefits against the cost. Some growers also prefer not to risk having leftover treated seed to deal with at the end of planting. However, this issue can be avoided by using hopper box treatments or other on-farm application equipment in some cases. If seed is treated on-farm, pay close attention to thorough coverage of the seed. Incomplete coverage can reduce the efficacy for the seed treatment.
There are many different seed treatments available for wheat. Although most seed treatment ingredients are fungicides, some will also contain insecticides. Each ingredient targets slightly different spectrum of disease causing fungi or insect pests. Therefore, many commercial formulations include combinations of ingredients that provide a broader spectrum of protection.
For more information, see K-State publication MF2955, Seed Treatment Fungicide Wheat Disease Management 2017 at: http://www.ksre.ksu.edu/bookstore/pubs/MF2955.pdf
Erick DeWolf, Extension Plant Pathology
Romulo Lollato, Extension Wheat Specialist