Image Credit: Alyssa Collins
In most of the region, 2018 has brought persistent moisture and prolonged warmth to our fields. If you are seeing alarmingly high levels of discolored beans in your bin, it is not because you are a bad farmer—our crops have simply been experiencing the perfect conditions for seed and pod rot development for a long time.
Several factors have come together to cause rot:
Fungi love moisture and mild temperatures
The weather conditions for the organisms that cause seed rots have been very conducive. In these situations, we say that disease pressure is high. So during this fall, the fungi that we typically see some of, and fungi that we almost never see, have been able to continue growing and invading plant tissues.
A mature plant is a dead plant
Once soybean plants mature and turn brown, they are no longer among the “living”. This means that some of the defense mechanisms that protect the plant from infection when it is growing will no longer be active. The longer a mature plant stands in the field, the more vulnerable the seeds and pods will be to disease-causing and opportunistic organisms.
Soybeans take up water naturally
As anyone who harvests beans knows, once they are mature, they can still take on moisture readily. Every time a seed takes up water and dries down again, it becomes more susceptible to invaders. If a bean swells enough, it can even split its pod open, leading to shatter and allowing additional water in which allows for more fungal growth.
Planting timing and maturity group is meaningful
All the above factors have led many to notice this final observation. As our planting system encourages earlier plantings of beans at various maturities, we may find that earlier planted fields have a different outcome than later plantings. For example, early planting works in our favor by allowing plants to build a canopy with the potential of having more nodes and pods than late planted soybeans, and sometimes it allows our crop to miss a dry spell at a critical growth stage. However, this year it seems that earlier planted beans are bearing the brunt of the harvest quality issues. This is probably a result of earlier maturation and the weather conditions keeping combines in the shed, leading to a longer time in the field before harvest. Other weather timing issues probably also play a role.
Now that we know what is causing these quality issues, what can be done? The good news is none of these fungi are associated with toxin production. So, you can feed these beans without concern for poisoning your animals. Do consult with your nutritionist to understand how nutritional value may change.
Be sure to dry harvested beans down to 13% moisture to halt the growth and spread of the fungi in storage. While they do not produce toxins, it is still important to preserve the quality you have.
Now that temperatures are cooling, these fungal problems will begin to slow in their progression. However, the damage already done will not get better. Harvest as soon as you can get the material through your combine and apply air and heat if possible.
Check with your buyer to understand their standards for payment this year before you harvest. Each elevator has different thresholds for acceptance and dockage in relation to damaged beans. Knowing this prior to harvest will allow you to assess your situation. If you suspect an unsaleable crop, contact your insurance agent. Do not try to take your own samples for an insurance claim.
For additional information on these and other disease issues, visit Crop Protection Network.