Crop Scene Investigation - 42 Solved: How did those devious dandelions get into a Perth winter wheat field?

Sunday, March 3, 2013

The dandelions growing in the Perth County winter wheat field escaped control a second time because the herbicide applied does not control dandelion.

The farmer missed the first opportunity to eliminate the dandelions at planting when the sprayer ran short of herbicide in the field, leaving a couple of hundred feet without herbicide application. Ontario Ministry of Agriculture, Food and Rural Affairs weed specialist Mike Cowbrough explains that the farmer really didn't have a second control opportunity because any herbicide that controls dandelion in the spring would also significantly injure and even kill the under-seeded red clover crop.  The farmer selected MCPA Sodium because it can safely be applied to winter wheat under-seeded to red clover. "Unfortunately, MCPA Sodium does not control dandelion," Cowbrough explains.

Generally, when it comes to dandelions, herbicides have a 20 per cent higher efficacy rating when applied in the fall compared to spring application. "They're much tougher in the spring and that's why I always recommend farmers go with a fall control strategy."

Cowbrough also notes the impact dandelions can have on winter wheat yields when not controlled effectively in the fall. "If you don't clear out those plants, you are going to have a significant impact on yield and stand establishment. Yield is set in the fall and it's very difficult to correct the ship in the spring." Congratulations to Jason DeWitt, Stratford, for his correct answer. BF