Striga Incidence Research Articles

Economic Analysis of Integrated Striga Management for Striga control as Influenced by Trap Crops and Inorganic Fertilizer Application in Sorghum [Sorghum bicolor (L.) Moench] at Fedis District, Eastern Ethiopia

Strigais problematic weed causing difficulty in cultivation of sorghum in areas of eastern hararghe where low and erratic rainfall is prevalent and soils are characterized by poor fertility. Knowing these different options of management has been tried however; its cost benefit has never been studied. Therefore, to assess its economic analysis and effect of integrated Striga management on Striga incidence, a field experiment was conducted during the cropping season of 2015 on heavily Striga-infested field in Fedis District, Boko site to determine the effect of trap crops (cowpea, soybean, desmodium, control) and N fertilizer rates (0, 46, 92 and 138 kg N ha-1) on management of Striga incidence and its economic analysis. The experiment was laid out in a factorial arrangement in a randomized complete block design (RCBD) with three replications. Trap crops were uprooted at maximum above ground fresh biomass. The results indicated significant (P<0.05) main effects of trap crop on emergence of Striga where the lowest (26%) Striga emergence of about was recorded over the control with use of cowpea.Striga count at harvest of sorghum was significantly (P< 0.05) affected by the interaction effect of trap crop and N fertilizer where 46 kg N ha-1 and use of cowpea as trap crop reduced the number of Striga seed bank by about 52.3% over the control treatment. The partial budget analysis also showed that the highest(47998.8 Birr ha-1) net benefit was obtained with the use of cowpea as a trap crop and 46kgN ha-1 application. Thus, the use of cowpea as trap crop and 46 kg N ha-1was found to be promising both agronomical and economically

Effects of Rotation with Trap Crops on Striga (Striga hermonthica Del. Benth) Incidence, its Seed Bank and Sorghum Growth and Yield

A trial was conducted for three consecutive seasons (2006/07,2007/08 and 2008/09) in a field artificially infested by Striga hermonthicain the Experimental Farm of the Faculty of Agriculture, University ofSinnar. The effects of a two seasons’ crop rotation on striga incidence, itsseed bank and growth and yield of subsequent sorghum crop wereinvestigated. The rotation comprised the trap crops, cowpea (Vignaunguiculata), millet (Pennisetum glaucum), sesame (Sesamum indicum),sunflower (Helianthus annuus) and fallows, in assorted combinations. Asorghum monoculture, for the three seasons, was included as a control.All treatments reduced striga emergence significantly in comparison tosorghum monoculture. Sunflower and sesame grown for two consecutiveseasons caused the maximum reductions (80%), while a fallow followedby sorghum resulted in the least reduction (42%). Significant reduction instriga capsules (37%) was caused by two consecutive sesame crops. In thesecond season, all treatments significantly reduced striga seed bank,. Twoconsecutive fallows and two consecutive crops each of cowpea, millet andsunflower resulted in the highest reductions in striga incidence (80% -92%), while a fallow followed by sorghum exhibited the least reduction(51-65%). None of the treatments had adverse effects on sorghum standearly in the season; however, at harvest significant reduction wasobserved. Sorghum monoculture resulted in the lowest stand, whilesunflower planted subsequent to a fallow and two successive sunflowercrops affected the highest stands. Among all treatments, sorghum

FARMERS’ PERCEPTION OF SORGHUM (SORGHUM bicolor [L.] Moench) PRODUCTION CONSTRAINTS AND TRAIT PREFERENCES IN NORTH EASTERN NIGERIA: IMPLICATIONS FOR STRIGA RESISTANCE BREEDING

The study was conducted to assess farmers’ perception of sorghum (Sorghum bicolor [L.] moench) production constraints and trait preferences in north eastern Nigeria: Implications for striga resistance breeding. Sorghum (Sorghum bicolor L. Moench), is globally an important cereal crop and a major staple crop in sub-Saharan Africa. However, its production is seriously constrained by myriads of biotic and abiotic problems. Combining pest resistance and good agronomic traits can increase sorghum productivity through systematic breeding programs. A field survey was conducted across three (3) States namely; Adamawa, Gombe and Bauchi selected in North Eastern Nigeria. The research was to determine farmers’ preferred traits and production constraints, with special emphasis on S. hermonthica and its breeding priorities. A multi-stage cluster sampling technique was employed to interview 156 farmers. Analysis of data revealed that majority (77%) of the respondents was subsistence farmers with a mean farm size of 6 hectares. Farmers identified inadequate capital, infestation due to striga incidence, drought and soil degradation as major sorghum production constraints. Incidence of striga was widespread (78.2%) across the three (3) States. About 83% of the respondents agreed that land degradation was the main cause of striga infestation. Majority of farmers (41%) considered yield as the most preferred trait in sorghum followed by early crop maturity (32.6%); and the most popular striga control measure was physical methods. To improve sorghum productivity, farmers preferred traits and production constraints need to be integrated into future breeding programs in order to improve level of adoption of new varieties.

A Diagnostic Appraisal of Sorghum Farming in Striga Endemic Areas of Eritrea

Sorghum (Sorghum bicolour (L.) Moench), the most important cereal crop in Eritrea, is grown in more than 210,000 ha annually but its productivity is hampered by many factors including: farmer perception, lack of appropriate varieties, undeveloped seed systems, drought stress and Striga infestation. This study was aimed at understanding the sorghum smallholder livelihoods, farming systems, Striga incidence and infestation levels, and types of varieties grown in Striga infested sorghum growing areas. A semi structured questionnaire and focused group discussions were used to gather information from a total of 136 randomly selected farmers from three Striga endemic sub-regions of Eritrea namely, Hamelmalo, Goluj, and Tesseney. The results indicated that the most important cereal crops in the study area were sorghum, pear millet, ground nut and sesame. The most important constraint to sorghum production was identified as drought stress followed by Striga infestation. The majority of the respondents (81.6%) reported that their sorghum was affected by Striga and the level of infestation varied from mild (10%) to severe (70% and above). Small-holder farmers also indicated that high grain yield, drought tolerance/resistance and Striga resistance were their most important criteria when selecting sorghum varieties. Up to 31 different landraces were listed as the most popular in the study area. The dominant source of seed for cultivation was the local varieties retained by farmers from previous harvests. The information documented from this study may be used in future as a basis for a participatory farmer-oriented sorghum breeding program.

Influence of triclopyr and nitrogen on management of Striga hermonthica on sorghum

Purpose – The purpose of this paper is to study the effects of the herbicide triclopyr, nitrogen and their combinations on Striga incidence and sorghum growth. Design/methodology/approach – A greenhouse study was undertaken in season 2013. Sorghum cv Wad Ahmed, urea and triclopyr were employed. Treatments were arranged in a randomized complete design with four replicates. Findings – Nitrogen alone suppressed the parasite completely early in the season. Triclopyr at 0.3 and 0.4 kg a.e. ha−1 reduced Striga emergence by 92.9 and 58.3 per cent early and late in the season, respectively. Triclopyr at 0.3 kg a.e. ha−1 applied subsequent to nitrogen at 43.8 kg ha−1 effected poor control of the parasite. Unrestricted Striga parasitism reduced sorghum height and chlorophyll content by 50.38 and 16.62 per cent, respectively. Triclopyr, nitrogen and their combination improved sorghum growth considerably. Originality/value – The results suggest that the herbicide when applied subsequent to nitrogen afforded the most consistent performance and resulted in the highest suppression of the parasite.

Assessment of the relationship between soil properties, Striga hermonthica infestation and the on-farm yields of maize in the dry Savannas of Nigeria

A study was conducted in Kano and Bauchi States in the dry Savanna of northern Nigeria to determine Striga incidence and infestation and relate these to soil fertility status and yield of maize. A three-stage sampling technique was used to select communities and fields in targeted Local Government Areas in the two States. The soils in the two States were generally of low fertility, characterized by low levels of total N, organic C, available P and exchangeable bases. In Kano State, Striga incidence ranged from 0 to 100%. One hundred percent of the maize fields sampled in Bauchi State had Striga. In general, Striga population was more than twice higher in Bauchi State [3.1 plants m−2] than in Kano State [1.4 plants m−2]. There were differences in Striga population and severity of attacks between the States and between communities within States. In Kano State, the Striga population was negatively related to latitude, total N, and exchangeable K and was positively related to sand and silt. In Bauchi State, Striga was negatively related to clay, exchangeable K, and Ca, and was positively related to pH and latitude. In both states, the Striga population was negatively correlated with maize grain yield. Up to 75% of the variations in maize grain yield in Kano State could be explained by Striga population and soil organic C. Management of Striga usually requires several measures, however, improving the levels of soil fertility should be the central component of any integrated Striga management approach.

Evaluation of Sorghum Genotypes Compatibility with Fusarium oxysporum under Striga Infestation

ABSTRACTCombined use of host resistance and Fusarium oxysporum as a biocontrol agent may provide enhanced management of Striga hermonthica (Delile) Benth. in sorghum [Sorghum bicolor (L.) Moench]. The objective of this study was to identify sorghum genotypes compatible with F. oxysporum and to determine the potential of this biocontrol agent for controlling Striga. Fifty sorghum genotypes were evaluated in the greenhouse in Striga‐infested soils with and without inoculation by F. oxysporum. A supplementary laboratory study was conducted to investigate the growth and proliferation of F. oxysporum in the soil and sorghum roots. Data were recorded on crop growth parameters, Striga incidence and colonization, and the persistence of F. oxysporum in the soil and on plant roots, using samples taken at 45 and 60 d after planting. Inoculation with F. oxysporum significantly shortened days to maturity compared to noninoculated plants. Plant height, biomass, panicle length, and seed yield per plant were higher in F. oxysporum treated pots. Striga emergence was delayed and vigor and overall incidence of the parasite was significantly reduced in Fusarium‐treated pots. The number of Fusarium colony forming units obtained from soil and plant samples were significantly different between genotypes. Three principal components (PCs) contributed to 67.31% of the total variation among the genotypes. Principal component 1, PC2, and PC3 contributed 27, 23, and 18%, respectively, to the total variance. Days to Striga emergence and Striga count and height correlated with PC1 while sorghum panicle length and plant height with PC2 and days to sorghum flowering and maturity with PC3. Thus, 12 promising sorghum lines were identified with farmer‐preferred agronomic traits and with F. oxysporum compatibility. This result is valuable in the development of Striga control in sorghum through integration of host resistance and F. oxysporum inoculation.

Increasing imazapyr-resistant maize yield by increasing plant density under natural Striga hermonthica infestation

Maize (Zea mays L.) is one of the most important crops in East Africa serving both as a staple food and cash crop to millions of people. As a vegetable, it is produced as green maize cobs, sweet corn or baby corn. Yields under farmers’ conditions in the Lake Victoria Basin average 1.3 t ha -1 which is less than 25% of the potential yield. This is attributed to several factors; the greatest being Striga (Striga hermonthica) which is a parasitic weed attacking several crops in the grass family. A medium term technological breakthrough in form of a herbicide (imazapyr) resistant maize variety has been developed to help reduce Striga infestation. The optimum maize plant population for effective seedbank reduction and optimum grain yield has however not been determined. The main objective of this study was therefore to evaluate the performance of imazapyr-resistant (IR) maize at different plant densities on Striga weed incidence and crop growth. The study was conducted for two seasons on a naturally infested Striga field in Western Kenya. The experiment was laid out as a split plot with three replications. Maize variety (treated IR maize, untreated IR maize and WH505/H516 commercial checks) was the main plot factor and density (44,444, 66,666 and 88,888 plants ha -1 ) as the sub-plot factor. Data was collected on maize stand, days to first Striga emergence, Striga incidence, Striga biomass, maize biomass and its yield components. Treated IR maize delayed Striga emergence on maize thus suppressing Striga parasitism. Any late Striga attachments had little or no effect on maize growth. Increasing the plant density of treated IR maize from 44,444 to 88,888 plants ha -1 did not affect Striga incidence but increased maize yield from 1.60 to 3.48 t ha -1 . It is therefore recommended that treated IR maize should be planted in Striga infested fields at 75cm x 15cm to hasten Striga seed bank reduction and maximize on maize yield to improve staple food availability.

Striga infestation in northern Cameroon: Magnitude, dynamics and implications for management

Surveys of Striga ( S. hermonthica (Del.) Benth.) infestation in northern Cameroon over the period 1987–2005 assessed Striga dynamics and evaluated its control strategies. In that period the percentage of Striga-infested fields increased in North and Far-North Provinces. Striga incidence increased more in maize fields than in the already heavily infested sorghum fields, where it remained almost constant. During the study period increased land pressure led to a reduction in the use of fallow and a higher frequency of cereal (mono-) cropping. Yields from farmers’ fields did not correlate with Striga incidence, confirming farmers’ prioritization of soil fertility, weeds, and labour for weeding as production constraints, rather than Striga. We discuss how conceptualization of Striga as a weed in the research arena may have led to a misunderstanding of farmers’ constraints. The decline of the cotton industry reduced farmers’ access to fertilizers, while access to organic manure remained limited, increasing the soil fertility constraint. We conclude that two decades of emphasis on Striga were unsuccessful. Enhanced crop yield through soil fertility management should be the entry point to tackle low yields and further worsening of the Striga situation.

Potential application of Hyptis spicigera for biological control of Striga hermonthica infestation.

Food situation has remained insecure and unpredictable in sub-Saharan Africa leading to high levels of cyclic famine and poverty. This has been exacerbated by perennial pest problems, which cause substantial pre- and post-harvest food grain losses. Production of cereal crops is threatened by Striga hermonthica weed known to infest an estimated 46000 ha of land in the traditional food producing areas in western and coastal Kenya. It is against this background that this study was designed to evaluate the efficacy of Hyptis spicigera–maize cropping systems on S. hermonthica infestation and maize grain yield and, generate a recommendation compatible with the target farmer dormains. Results showed that Striga counts were significantly (P < 0.05) reduced where maize was following fallow with H. spicigera. This was most effective in reducing S. hermonthica incidence and increased maize yield from 2.2 to 3.4 T/Ha. Intercropping maize and H. spicigera in the same plot at the same time negatively affected maize growth resulting in reduced maize yields. Indications were that root cuttings of H. spicigera stimulated Striga seed germination while their stubble (stem and leaves) reduced Striga seed bank in the soil. Striga seed bank analysis showed that Striga seed depletion increased with increase in Hyptis bushes with critical Hyptis seeding rate of 3 kg/Ha for maximum reduction in Striga seed bank. The findings of this study have implications for plant protection against S. hermonthica and improvement of cereal crop production in Striga-prone environments. Key words: Striga Incidence, seeding rates, cropping systems, maize yield.

On-farm evaluation of improved maize varieties intercropped with some legumes in the control of Striga in the Northern Guinea savanna of Nigeria

Witchweed ( Striga spp.) is one of the major threats to cereal production in the West African savanna. Two on-farm trials were conducted in 1999 and 2000 at Layin Taki and Kayawa to evaluate the use of tolerant maize varieties intercropped with some legumes in the management of the parasitic weed. Striga incidence and maize reaction score were significantly ( P=0.05) reduced by the variety Acr.97 TZL Comp. 1 intercropped with soyabean (var. SAMSOY II) and groundnut (var. RMP-91) in both years and by Oba Super 1 intercropped with the two legumes in 2000. Oba Super 1+RMP-91 increased cob numbers and weight and grain yield over the local cultivar in the two years. Acr.97 TZL Comp. 1+RMP-91 increased cob number and weight in both the years and grain yield in 1999. Grain yield and cob weight had significant ( P=0.05) negative correlations with Striga incidence and crop reaction score. Intercropping the two improved varieties with either soyabean or groundnut was more profitable than the local cultivar grown alone.

EVALUATION OF INTEGRATED STRIGA HERMONTHICA CONTROL TECHNOLOGIES UNDER FARMER MANAGEMENT

On-farm trials were conducted in the northern Guinea savanna of Nigeria. The objective was to compare integrated Striga hermonthica control measures (soyabean or cowpea trap crop in the first year followed by maize resistant to Striga in the second year) with farmers' traditional practices (cereal-based cropping systems) under farmer-managed conditions.Integrated control proved to be highly effective in terms of reducing Striga incidence both in terms of reduced seed density in the soil and decreased infection in maize. Resistant maize following the soyabean trap crop yielded 1.58 t ha−1 of grain and out-yielded local maize following traditional practices by more than 80%. Similarly, the overall productivity over the period of the experiment was highest with the integrated control treatment using soyabean. Conversely, resistant maize after the cowpea trap crop yielded only 0.92 t ha−1 (possibly due to the poor performance of the cowpea crop in the first year), and maize yields were similar to those obtained with farmer practices. Initial Striga seed density in the soil was negatively correlated (r = −0.33) with soil nitrogen, but nitrogen-fertilizer application rates did not seem to affect the level of Striga infection in maize.

Where Once There was Grain to Burn: A Farming System in Crisis in Eastern Malawi

The parasitic weed Striga asiatica is a serious problem in maize crops in southern Malawi and much of the rest of southern Africa. The authors spent two years studying farmer knowledge of the weed in an area of south-eastern Malawi, and the links between population pressure, soil fertility and Striga incidence. Following a discussion of the history of the study village, the results of a series of field trials are presented which test the effect of altered fertilizer applications on yields of maize plants in Striga infested areas. These show that simply changing the timing of fertilizer application, using the rates farmers currently use, could have a dramatic effect on the maize plant's ability to cope with the weed and on the economics of maize production.

Diseases and parasitic weeds of sorghum in Tanzania: occurrence and incidence, 1986–1990

Sorghum is an important subsistence crop in Tanzania. Surveys were carried out between the 1986 and 1990 crop seasons to determine the prevalence of diseases and parasitic weeds in the major sorghum-growing areas of Tanzania. Twenty diseases of sorghum and three parastic weeds were observed. Grain moulds (several fungi), grey leaf spot ( Cercospora sorghi), anthracnose ( Colletotrichum graminicola), rust ( Puccinia purpurea), leaf blight ( Exserohilum turcicum), ladder leaf spot ( Cercospora fusimaculans), sooty stripe ( Ramulispora sorghi) and zonate leaf spot ( Gleocercospora sorghi), were economically important diseases. Striga asiatica was the most common parasitic weed in Tanzania. Ilonga in the low-altitude (⩽ 1000 m) zone and Hombolo in the mid-altitude (> 1000 m) zone were identified as locations with a high frequency of diseases and striga incidence. These locations were recommended for resistance screening against most of the leaf diseases, grain moulds and S. asiatica.

Fusarium nygamai, a potential bioherbicide for Striga hermonthica control in sorghum

Abstract Glasshouse trials were performed to investigate the control of the parasitic weed Striga hermonthica by Fusarium nygamai and the performance of the host plant sorghum (Sorghum bicolor) using different inoculum substrates and inoculum amounts of the fungus. Optimal constant and alternating temperatures for the growth of the fungus were 25°C and 30 20° C , respectively. Striga incidence was decreased up to 100% when the fungus was incorporated into the soil preplanting. Emerged Striga plants at different stages of growth up to the flowering stage were killed by the fungus when the fungus was applied postemergent. In root-chamber trials none of the Striga seeds germinated when 10 ml inoculum suspension of 8 × 106 spores/ml of F. nygamai was applied on seeds of the parasitic weed sprinkled on the surface of filter paper. F. nygamai has potential as a bioherbicide for Striga control. Further studies regarding its performance under field conditions and its safety to the environment and humans should be assessed.

The effect of soil temperature, moisture and nitrogen on Striga asiatica (L.) Kuntze seed germination, viability and emergence on sorghum (Sorghum bicolor L. Moench) roots under field conditions

Experiments were conducted in a Striga-sick field to study the effect of soil temperature, moisture and nitrogen on Striga parasitism on sorghum. Striga seeds contained in nylon bags and buried at 2 cm in the soil, were exposed to different temperature and moisture treatments. Clear polythene, hay mulch and bare soil treatments were used to vary soil temperature. These treatments gave mean maximum temperatures of 60°, 48° and 37°C, respectively at 2-cm soil depth. Irrigation levels of 0, 30 and 60 mm were applied to change soil moisture. Striga seed germination, viability and emergence were studied. After 34 days of preconditioning, the exhumed Striga seeds from polythene-covered plots (solarized plots) did not germinate or retain viability when these seeds were exposed to sorghum root exudate. However, seeds similarly buried under hay mulch or bare soil, with mean maximum soil temperatures of 48° and 37°C, respectively, had similar germination and viability percentages. Of these 75% germinated and 85% of them were viable, regardless of the temperature treatment. Although seeds stored at high temperature and humidity (solarization) were killed, more Striga plants emerged under the polythene treatment compared to hay mulch and bare soil treatments. The observed Striga plants in the polythene mulch treatment were, therefore, assumed to have come from deeper layers where solarization was not effective. Irrigation treatments did not have significant effects on Striga seed germination and viability, but a slightly higher number of plants emerged at 60-mm irrigation level than at 30-mm and 0-mm. Striga emergence, on the other hand, was directly related to the rate of N application. Nitrogen rates of 0, 25, 50 and 100 kg ha−1 resulted in the emergence of 11, 34, 38 and 40 Striga plants per plot, respectively. Despite the high infestation at high N levels, sorghum plants did not show a loss of vigor. Nitrogen application, therefore, does not reduce Striga incidence, but seems to neutralize the harmful effects of Striga without reducing the extent of parasitism.