Seed Dressing Maize with Imazapyr to Control Striga hermonthica in Farmers’ Fields in the Savannas of Nigeria

Abstract

Use of small doses of imazapyr and pyrithiobac for seed coatings of imazapyr-resistant maize hybrids (IR-Maize) offers an effective means to control Striga hermonthica. Field trials were conducted in Bauchi and Kano States of Nigeria in 2014 and 2015 under heavy Striga infestation to evaluate the potential effectiveness of herbicide coated hybrids maize on Striga control in farmers’ field. Results showed that herbicide coated seeds reduced number of emerged Striga per m2 and Striga damage symptoms in farmers’ fields in all the locations. In Kano the number of emerged Striga was 4.9 to 7.9 times less in herbicide treated hybrids in comparison with those of the same hybrids planted without herbicide treatment. The Striga-resistant open pollinated variety (OPV) (TZL COMP1 SYN) had 6.7 to 8.0 times more Striga than the treated hybrids. In Bauchi, the number of emerged Striga on the untreated IR-maize hybrids were over four-times higher on the treated IR-maize hybrids than on the untreated hybrids. The Striga-resistant OPV check had four-times more Striga than the treated IR-maize hybrids and twice more than the untreated IR-maize hybrids across the two years. However, the effects of herbicide seed coating on grain yields were not consistent because of strong seasonal effects. The result revealed that coating of imazapyr-resistant hybrid maize seeds with imazapyr was effective in reducing Striga infestation in farmers’ fields. Although herbicide seed coating did not give consistent yield advantages of the hybrids over the untreated checks, a combination of herbicide seed treatment and genetic resistance to Striga would serve as an effective integrated approach that could significantly reduce the parasite seed bank from the soil and prevent production of new seeds. The IR-hybrids and the OPV checks contained Striga resistance/tolerant genes that protected them against drastic yield loss in the Striga infested fields in both Bauchi and Kano.

Effects of Maize (Zea Mays L.) Hybrids and Nitrogen Application on Striga Infection and Grain Yield under Natural Infestation with the Parasitic Weed Striga Hermonthica

“…Our results show that varieties or hybrids that are bred for low Striga emergence and damage produced higher grain yields in fields naturally infested with Striga, consistent with findings of Kamara [8]. In on-farm soybean maize rotation experiment in northern Nigeria, Kamara et al [21] reported that continuously grown Striga-resistant maize varieties produced grain yields similar to that of Striga-resistant maize variety grown after soybean but had higher grain yields than the local susceptible maize hybrids. The higher dry matter and grain yields recorded in the new DTSTR hybrids may be due to the combined effects of N application and lower Striga infection and damage.…”

“…Several methods have been recommended for the control of Striga in maize. These include the use of Striga-tolerant or resistant maize cultivars [18][19][20], application of nitrogen particularly for poor soils [8,14,21,22), legume-maize rotation [23][24][25][26], herbicide seed coating [21,27]. Maize breeders at the International Institute of Tropical Agriculture (IITA) have considered breeding for polygenic resistance to S. hermonthica as a viable approach to provide durable protection to the crop against diverse parasite populations [19].…”

Identification of QTLs Controlling Resistance/Tolerance to Striga hermonthica in an Extra-Early Maturing Yellow Maize Population

“…The subsistence farmers are usually the most severely affected. The extent to which S. hermonthica affects the growth of its host varies tremendously, depending on the level of host plant resistance/tolerance, extent of infestation, and the prevailing environmental conditions [9,10]. Resistance to Striga denotes the capability of the host plant to induce the germination of Striga seeds but prevents the parasite from attaching to the roots of the maize plants or kills the attached parasitic plants.…”

Striga Biology and Its Management in Maize: A Review

“…Combination between host resistance and Fusarium oxysporum-based mycoherbicide caused effective Striga reduction and increased crop yield [82]. Similarly, the reduction in Striga infestation achieved through seed coating of imazapyr-resistant hybrid maize can be significantly further increased by exploiting maize Striga-resistance [83]. Recently, combining conservation agriculture practices, such as cover cropping and fertilizer applications, with Striga-resistant varieties was found to alleviate Striga impact on rice and maize [84].…”