Witchweed [Striga hermonthica (Del.) Benth] control using imazapyr seed coating in maize hybrids in the Nigerian savannah

Abstract

Witchweed [Striga hermonthica (Del.) Benth] is a major parasitic weed of most cereal crops in Africa, including maize. Seed treatment with low doses of acetolactate synthase–inhibiting herbicides, such as imazapyr, was introduced in the 1990s to control witchweed. Field trials were conducted in four locations in Nigeria in 2007 and 2008, to assess the effect of coating seeds of several maize hybrids with imazapyr on witchweed control. The hybrids had genes for imidazolinone herbicide resistance (IR), as well as genetic tolerance to witchweed (ST). Treatments were 12 IR maize hybrids with ST and three checks without the IR gene (commercial, witchweed tolerant, and witchweed susceptible hybrids). Averaged across all locations, the coated IR hybrids with ST yielded more and supported fewer witchweed plants than the uncoated IR hybrids with ST. The IR hybrids with ST yielded 57%–60% more than the commercial and witchweed tolerant hybrid checks that were not coated. The witchweed susceptible hybrid check suffered a yield loss of 88% under infestation without seed coating. The IR hybrids with ST yielded 3564 kg ha−1 of grain when coated with imazapyr and 3266 kg ha−1 otherwise. The findings indicate that coating of IR/ST maize seeds with imazapyr improved tolerance to witchweed.

Effectiveness of Imazapyr Coated Hybrids and Selected Striga-tolerant Varieties on <i>S. hermonthica</i> Management and Maize Yield Performance in Western Part of Kenya

“…IRM genotypes varieties reduced the number of shoots that had flowered in both locations. This results correlate with other studies [8,22]. Similarly, it has been noted that using herbicide coated seed reduced striga weed density in the farmer's field by 4.9-7.9 compared to when susceptible varieties were used [29].…”

“…Stunted growth observed in commercial genotypes used in this study was attributed to early striga parasitism and high weed density that caused maize-weed competition for water, nutrients and light. Additionally, it has also been indicated that using IR coated genotypes reduces the effects of striga weed on maize height [8]. In a study on harmful effects of weeds on maize performance results showed that competition for growth factors by weeds reduces the height of maize and ultimately the yield [36,38].…”

Unraveling Seed Dormancy and Host Specificity of Alectra Vogelii in Malawi

“…Cardoso et al (2011), Kabambe et al (2014), and Gwatidzo et al (2020) reported that higher yields were observed on resistant varieties which agreed with the current findings. This indicated that the Alectra reaction had an impact on the amount of yield on IT82E-16 as it was highly susceptible to the parasitic weed and it was not a surprise to observe as susceptible cowpea varieties suffer yield reduction up to 100 % in a field situation (Boukar et al, 2016;CABI, 2017;Chikoye et al, 2020).…”