By Scout Nelson
Waterhemp is one of the most difficult weeds to control in South Dakota’s row crop fields. Its fast growth and resistance to herbicides make it a serious threat to crop health and yields.
Waterhemp can grow about one inch per day when temperatures are warm and the soil has enough moisture. This fast growth allows it to compete with crops for sunlight, water, and nutrients.
Waterhemp plants are dioecious, meaning they have separate male and female plants. Male plants bloom first, helping to pollinate female flowers. If not controlled, just one female waterhemp plant can produce hundreds to hundreds of thousands of seeds.
The flowering process in waterhemp depends on the amount of daylight, or photoperiod. When the days get shorter in August, flowering usually begins. However, heavy shading can make plants flower earlier than usual. Flowering was already seen in early July, which is earlier than expected.
Male waterhemp flowers feel soft and may release yellow pollen when touched. Female flowers have sharp bracts and white stigmas that collect pollen. Once pollination happens, seeds can begin to form in about a week.
The early-flowering waterhemp has not produced seeds. This offers farmers a chance to act before the weed spreads further. It is important to control waterhemp when it is still small—about 2 to 4 inches tall. Delaying control may lead to more seeds in the field, causing bigger problems in the next growing season.
Farmers should scout fields regularly to monitor the growth and flowering stage of waterhemp. Use approved herbicides and follow guidance from the latest South Dakota Pest Management Guides.
Photo Credit: gettyimages-mvburling
Categories: South Dakota, Crops, General