This article appears in the April 2016 issue of Potato Grower.
When considering weed control, the first thing that comes to mind is usually the use of herbicides. While proper, timely herbicide application is an integral part of just about any effective weed control program, there are several other ways by which growers can ensure their potato crop doesn’t face too much competition.
- Monitoring
“To plan a weed management program, you must know what kinds of weeds are present, which ones are most abundant, and whether their abundance is changing,” write Joe Nuñez and Harry Carlson of University of California Extension. Nuñez and Carlson recommend growers regularly survey each of their fields to determine which species of weeds are present and the effectiveness of previous weed control measures. Weekly surveys should be made during the early part of potato season. Scout field before and after applications to inform future application decisions.
- Prevention
Weed seed, much like fungal spores and insect pests, often hitches a ride on equipment from one field to another. Pamela Hutchinson and Charlotte Eberlein with University of Idaho Extension recommend cleaning equipment before moving to another field and screening irrigation water when possible.
- Cultural Practices
Many cultural practices are available that reduce weed emergence and inhibit herbicide resistance. Among the most important of these practices are thoughtful selection of rotation crops and timeliness of cultivation. Several studies investigating the effectiveness of green manures and cover crops in weed reduction in potatoes are currently under way at several sites across the U.S.
“Employ different cultural practices each year to reduce the risk of developing resistant populations,” say Hutchinson and Eberlein.
- Variety Selection
While many weeds can be effectively controlled through normal cultural practices, a few, including nutsedges and nightshades, are more difficult to suppress. However, many potato varieties are very competitive with weeds and can even be successfully grown without the use of herbicides, depending on a farm’s particular location and mode of operation. According to Nuñez and Carlson, varieties that achieve early row closure and are successfully competitive against weed infestations include White Rose, Ute Russet, Chieftain and Red La Soda.
- Herbicides
Of course, proper herbicide application is a very effective way to control weeds in a potato crop. Hutchinson and Eberlein offer several helpful tips to getting the most out of an herbicide program. These include: avoid sequential applications of the same herbicide in a growing season; tank mix herbicides with different modes of action; use tank mixtures that include herbicides with overlapping weed spectrums.