L. Garciatorres et al., IMAZAPYR APPLIED POSTEMERGENCE IN SUNFLOWER (HELIANTHUS-ANNUUS) FOR BROOMRAPE (OROBANCHE CERNUA) CONTROL, Weed technology, 9(4), 1995, pp. 819-824
Field studies were conducted from 1991 through 1994 in several locatio
ns of Southern Spain to determine the efficacy of imazapyr as late pos
temergence application in sunflower for broomrape control and the crop
response to this herbicide under weed-free conditions. Single applica
tions of imazapyr at 10 to 15 g/ha on sunflower plants at about the V1
2 (12 leaves) to V19 (19 leaves) growth stages, infected with broomrap
e plants at the predominant growth stages ''c'' (small nodule with sho
ot bud visible) and ''d'' (shoot bud and roots well developed), result
ed in effective control without damaging the crop. Double applications
of imazapyr at 10 + 10 g/ha at about the same crop growth stages V12
to V19, at a time interval of 12 to 14 d between single applications,
were also efficacious and well tolerated by the crop. The same herbici
de treatments applied to weed-free sunflower did not adversely affect
the biomass, head diameter or yield of the crop as compared with the n
ontreated check. As a result of the low rate of imazapyr required for
broomrape control, the herbicide treatments are economical (about $3 t
o $6/ha), non-residual and not affected by the type of soil texture an
d rainfall conditions.