Imazapyr and pyrithiobac movement in soil and from maize seed coats to control Striga in legume intercropping

• Published in: Crop protection Vol. 21; no. 8; pp. 611 - 619
• Main Authors: Kanampiu, Fred K., Ransom, Joel K., Friesen, Dennis, Gressel, Jonathan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-09-2002
• Subjects: Beans; Cowpeas; Herbicide movement; Intercropping distances; Witchweed; Yellow gram; Intercropping distances; Beans; Yellow gram; Herbicide movement; Witchweed; Cowpeas
• ISSN: 0261-2194; 1873-6904
• DOI: 10.1016/S0261-2194(01)00151-X

Imazapyr and pyrithiobac dressed to seeds of imidazolinone-resistant maize effectively control
Striga hermonthica (witchweed). The effects of the movement of these herbicides in the soil and in maize plants was measured on
Striga germination and on legumes intercropped with maize.
Striga seeds were killed when high rates of either herbicide percolated through simulated soil columns; almost no viable
Striga seeds remained in the upper 10
cm, and >80% were killed at 30
cm. The herbicides applied to maize leaf whorls moved systemically out of roots, killing attached and germinating
Striga. Sensitive crops (beans, cowpea, and yellow gram) were unaffected when planted at >15
cm from maize coated with 0.4
mg a.i. pyrithiobac or 0.84
mg a.i. imazapyr seed
−1, but were severely inhibited when planted within 12
cm. Simple herbicide seed coatings are thus compatible with commonly used African intercropping systems, while facilitating maize growth and depleting the
Striga seed bank.