- Author: Amber C. Vinchesi
I have only received one weed-related farm call in my two seasons as the vegetable crop advisor in Colusa, Sutter and Yuba counties.
In early August 2017, one of the melon PCAs I work with called me up to tell me about a grassy weed in a fresh-market honeydew field. He found the weed in two fields and had never seen it before in melons. Within the field, the weed was interspersed among the melon plants in the plant beds and was extremely easy to pull out of the ground. It popped right up.
He sprayed sethoxydim (Poast) twice, because the weed kept growing back. The weed was not flowering and the rhizome was not well-developed.
The first time Poast was sprayed was to control the grass. When the weed came back, they thought they may not have had good coverage on the spray, so they applied Poast again. But the grass still rebounded, even though he had success with sethoxydim in the past on other grasses. I believe this is why he called me out to the field: 1) the weed kept coming back and 2) he and the grower wanted a weed ID to determine if the weed would be a future issue.
I sent photos to the Weed Workgroup and the consensus was that this weed was Johnsongrass, most likely from seed. I confirmed this diagnosis with the Sutter County Ag Commissioner's office who noted that it was definitely Johnsongrass, but very abused Johnsongrass (perhaps from two applications of Poast). When I informed the PCA of the weed ID, he was shocked. In his many years working in melons and other crops, he has never seen Johnsongrass in a melon field. And as a non-weed scientist, I would not know if this is significant or just a rare occurrence. Also, as a non-weed scientist, I am very grateful to the the Weed Workgroup and those weed scientists that helped me out with this diagnosis.