The institute, in a report published June 6, said the herbicides have excellent efficiency against broadleaf weeds and grasses for up to eight weeks after planting cassava when combined with good agronomic practices.
“These treatments plus one post weed control at 10 weeks after planting resulted in root yields that more than doubled the national average in Nigeria,” the report said.
“The pre-emergence herbicide application alone, at rates safe for cassava, did not provide adequate season-long weed control.
“Therefore, the researchers recommend one supplemental post weed control to supplement the herbicides.”
IITA is a non-profit institution that offers leading research partnership that facilitates agricultural solutions to hunger, poverty, and natural resource degradation throughout sub-Saharan Africa.
According to the report, the most damaging effects of weeds on cassava occur during two periods, the first two to three weeks after planting when the growth rate is still low, and in the third month after planting as the roots start forming.
In the report, the recommended weeding schedule for cassava is at four, eight and 12 weeks after planting in the first growth phase.
The report notes that most farmers do not weed their fields on time, given the costly and backbreaking nature of hand hoe weeding, on which the majority of African farmers depend.
“Delayed weeding leads to reduced yields since weeds compete with cassava for nutrients,” it said. “Given the difficulties of using hand-held hoes, several farmers in Nigeria are resorting to herbicides for weed control.”
The report pointed out that the most common pre-emergence herbicides used in Nigeria by cassava farmers are formulations containing atrazine, diuron and S-metolachlor.
“These herbicides need to be applied at high doses if they are to be effective, which makes them quite expensive for smallholder farmers.
“It is, therefore, essential to provide farmers with an efficient and affordable weed management system to enhance cassava yields,” the report said.
The report identifies Fierce 75 WG, Merlin 75 WG, Bullet 700 SC, Gardoprim plus Gold 500 SC and Lagon 575 SC as alternatives.