Although scab was not widespread in Ohio this year, there were a few pockets with high levels of the disease in some parts of the state. In addition, persistent rainfall over the last several weeks has caused producers to be concerned about grain quality even in fields without high levels of scab. One of the main questions being asked is whether scab will affect the quality of the wheat seed this fall.
Yes, scab will indeed reduce seed quality tremendously, causing germination rates and stands to plummet. However, the vomitoxin that is usually present in scabby seed is not your biggest problem in terms seed germination, damage to the embryo is your problem. You should first pull a grain sample from your lot and determine how badly damaged the kernels are.
You can do this by estimating the percentage of Fusarium damage kernels (FDK) – small, shriveled, light-weight, and discolored (pinkish-white) seeds. FDK will give you a very good measure of seed quality.
If you have more than 30-40% FDK, then I would suggest not using your scabby wheat for seed. However, if you absolutely HAVE to plant scabby wheat, cleaning, germ test, and fungicide seed treatment are absolutely necessary. Seed treatment will only help to a point, but you should still treat the seed and try to do so as soon as possible to reduce further fungal growth.
Cleaning will get rid of light, scabby materials, and this will naturally increase the test weight of the lot. If you can increase the test weight to about 56 lb/bu after cleaning and your germination rate is above 80%, then you have decent quality seed. Gravity table would be your best option for cleaning. In addition to cleaning and treating, seeds should be stored under cool, dry conditions until planting to prevent mold development.
Blending of scabby wheat with healthy wheat is another good option to increase the overall quality of the lot. Increasing the seeding rate will also be helpful, but you should determine percent germination first – this will help you to adjust your seeding rate accordingly.
So, here is what I will recommend:
1- Avoid planting scabby wheat, but if you absolutely have to or choose to
2- Clean the seed as well as you can;
3- Treat the seed as soon as possible after harvest and store it in a cool, dry place;
4- Determine germination rate before planting;
5- Increase seeding rate is your germination rate is below 80%.