Effects of Aqueous Neem Extract, 2,4-D and Urea on Striga hermonthica (Del.) Benth. on Millet

Abstract

This investigation was carried out in West Kordufan State, at Elfula. Where the soil is of low fertility and is highly infested with Striga hermonthica. Field and laboratory studies were undertaken to investigate the best control methods for Striga. In the study the effects of neem seeds powder, neem leaf and seed extract, urea and 2, 4-D on Striga incidence on millet and on millet roots length and Striga germination were determined. Treatments were arranged in randomize complete block design (RCBD) with four replicates. Field results showed that, neem seed powder, urea and 2, 4-D reduced Striga emergence by 25 to 75%. Neem seed powder at 126 and 168 kg/fed in combination with urea and 2, 4-D reduced Striga emergence by 25 to 66%. 2, 4- D applied subsequent to urea reduced Striga emergence significantly. Neem seed powder at 168 kg/fed plus urea, as single and split dose increased crop height significantly. 2, 4-D in combination with urea or neem seed powder at 168 kg/fed did not affect millet height in one season, but a significant increase in height was realized in the second season. 2, 4-D applied subsequent to urea as single and split dose increased millet height significantly. Neem seed powder at 168 kg/fed reduced grain yield significantly. Neem seed powder at 126 kg/fed, 2, 4-D alone, irrespective of dose, urea as single and split dose, the combination of neem seed powder and urea, neem seed powder and 2, ii 4-D, urea and 2, 4-D increased grain yield, albeit not significantly. Laboratory experiments showed that, neem leaf and seed extract, irrespective of dilution, reduced millet root length significantly. However, the attained reductions decreased with decreasing concentration. Neem leaf and seed extract at 1.25, 2.5 and 5% (g/100ml), applied to Striga seeds conditional in water reduced Striga germination significantly, and reduced Striga radical length, considerably. 2, 4-D and urea increased germination of Striga seeds significantly and reduced radical length considerably. Striga seeds conditioned in neem leaf extract, neem seed extract and urea displayed low germination when placed in the vicinity of millet roots. Striga seeds conditioned in 2, 4-D or GR24 in water and subsequently treated with root millet, displayed high germination, when placed in close proximity to millet roots. The study showed that neem leaf and seed powder, urea and 2, 4-D have negative effects on Striga parasitism on pearl millet. Reduced parasitism may be attributed to reduced germination and reduced length of Striga radical and millet roots. Other possibilities including inhibition of haustorium initiation and/or induction of pre-mature haustoria cannot be ruled out.