By Alyssa Collins
It’s this time of year that we begin to see more disease issues in corn and beans.
This is partly because late July and August is a reliably humid time in the Mid-Atlantic, and those fungi and bacteria just love moisture. But the other thing happening right now is that the plants are entering a period of intense growth and reproduction. This means that a “hidden” infection that may have been present since very early in the season may now start to show symptoms. For instance, a soybean root infection that got established back in May is only now becoming obvious, because the plant’s damaged roots can no longer keep up with the water and nutrient needs of the expanding canopy and pod formation.
Last week, I wrote a bit about how to determine if a fungicide application would be appropriate for your corn or beans. And this week Anne Dorrance at Ohio State shares some of her research on profitable soybean fungicide applications.
But here, let’s talk about the resources you have to make sure you know your enemy. This is important, because not all diseases can be treated with fungicides.
There are some diseases that you can probably be pretty comfortable diagnosing yourself, because they are commonly seen each year. Things like Northern corn leaf blight and Grey leaf spot in corn and Brown spot or Frogeye leaf spot in beans are easier to identify. But then there are diseases or other problems that may not be so clear. In this case, you have a number of resources to help you out with the ones that stump you.
First, you probably know to contact your county extension educator.The educators have a lot of experience and have access to literature and other resources that can help in identification. They also know the questions to ask in order to get all the necessary information to solve the problem.
But did you also know that Penn State has a plant disease clinic where you may submit samples for identification as a grower in Pennsylvania? Sample analysis is provided free of charge for PA farmers, but you will need to do a little work to get the best results. You can find information on how to take and send a sample as well as the submission form here.
The most important thing you can do is fill out the form completely. A diagnostician can only give you an accurate answer when they have all the information. Otherwise, finding the cause of the problem is like looking for a needle in a haystack. Remember, once your sample gets to the lab, the folks there just have one or a few plants to work with. They’ll also need the information that only you can provide such as how much of the field is affected, when did the problem start, what is the pattern in the field, what varieties are you growing, and more to solve the mystery.