As growers move around spraying their last herbicide for weed control and begin to put out fungicide they are evaluating peanut stands from field to field. It’s no secret we had issues with seed quality this year. So now that peanuts are up, why do you still see dying plants in spots? It can be a few different things. But one I wanted to point out that I am seeing in abundance this year is, Aspergillus crown rot. Some early planted peanuts are past this being an issue but we had a good bit of late planted peanuts in the county this year.
Peanut seed saved from last year went through a lot of hot and dry weather. This can lead to a build up of pathogens in and on the seed. Good seed treatment and in-furrow fungicide applications can and do help, but sometimes that is not enough. When the pathogen is present in high numbers and conditions in the soil are just right it can still explode to cause problems in the field. The pathogen can be housed in the seed itself and grow into the hypocotyl, the portion of the plant found just below the soil line. If you see dead plants in a row and dig them up to find a black smutty looking growth at the soil line, then you have Aspergillus crown rot. Peanuts usually get crown rot around 14 days after planting. The problem can persist up to 40 days after planting. If affected plants live past that, they will recover.
There is nothing a grower can do after the seed has been planted. The best thing for the crop is to get rain to cool the soil and prevent moisture stress to the peanuts. These dying plants look bad and it can be alarming. But in most years in fields with a good stand, plant death from crown rot does not cause significant yield loss. In years like 2020 when stands were not great to start with, we may see differently.