Joel Ransom

Dicamba (2-methoxy-3,6-dichlorobenzoic acid) has been shown to be effective in controlling Striga asiatica in maize in the USA. Experiments were therefore conducted from 1990 to 1992 to evaluate its effectiveness against S. hermonthica in Western Kenya. Dicamba was more effective when applied at the rate of 0.75 kg a.i. ha-1 compared to 0.50 kg a.i. ha-1. Applying dicamba over the top of maize plants or post-directing it to the lower plant part did not significantly affect its effectiveness. Application at 30 days after planting was not as effective as delaying the application to 45 days after planting. Crop injury was observed early in a few cases, though the affected plants later recovered and yield was not affected. Dicamba was not persistent as Striga emerged later in the season. Although dicamba can provide some control early in the season, its low persistence implies that other control measures need to be integrated with it to avoid subsequent seed production by the Striga pla...

In the humid and sub-humid East African highlands, soil fertility situations are more serious due to continuous cropping with little or no external inputs and removal of crop residues. As a result, sustainability of soil productivity has been under threat due to continuous soil fertility depletion. The problem can be alleviated by inclusion of legumes in crop rotations and retention

Acetolactate synthase (ALS)‐inhibiting imidazolinone and sulphonylurea herbicides have been found to be effective in selectively controlling the pernicious parasitic weeds Orobanche, Striga and Alectra spp. in some crops. This control could be effected both as whole field applications and as seed dressings. Weeds rapidly evolve resistance to this single‐target, high mutation frequency group of herbicides, which usually exert heavy selection pressure. This type of rapid evolution of resistant populations was previously predicted by models, and later validated in the field in other weed and cropping situations. The selection pressure of this herbicide group may be exceedingly strong with parasitic weeds, as they are controlled by very low dose rates and the doses used are in the ‘overkill’ range. A good management strategy with non‐parasitic weeds was to lower selection pressure, but this may be less effective with parasitic weeds. Many of the areas of the world where parasitic weeds ...

ABSTRACT Striga hermonthica is a major threat to cereal production in western Kenya and other parts of the world. In laboratory experiments, maize and sorghum showed some resistance to late Striga attachment and parasitism. Field experiments were conducted in 1996 and 1997 in western Kenya to assess the effect of transplanting maize and sorghum, under rain-fed field conditions, on grain yield and Striga parasitism. In transplanted sorghum, Striga emergence was not reduced and sorghum failed to produce grain yield in three out of four seasons. Transplanting maize in all experiments significantly increased grain yield compared to direct seeding. The improved productivity was largely associated with less Striga attachment. Striga densities were considerably lower if maize seedlings were more than 17 d old at transplanting, with decreasing levels of Striga with increasing age of the maize seedlings. Seedlings transplanted before they were 15 d old did not reduce Striga attachment. Transplanting maize under rain-fed conditions is probably only suitable for small areas that are highly infested with Striga, due to its high labor requirements. Under these conditions, crop yield can be more than doubled. An incentive to using this method by small-scale farmers would be that the main input at risk is their own labor. However, the establishment of nurseries and the timing of the transplanting operation require a certain level of farm management that could constrain the adoption of this technique. Nomenclature: Striga hermonthica (Del.) Benth; maize = corn, Zea mays L. ‘Hybrid 511’; sorghum, Sorghum bicolor (L.) Moench ‘Seredo’.

... We thank the Natural Resources Institute for financial support (project X0245), and are grateful for the help and support of staff at CIMMYT and the Kenya Agricultural Research Institute, especially Mr George Odhiambo and Dr M Osoro for their special assistance. References ...

... end-use quality, and is dependent on several factors including environ-ment, fertilizer N rate, N application timing, genotype, and the interaction of these factors (Terman, 1979; Rao et al., 1993; Garrido-Lestache et al ... Brian N. Otteson, Mohamed Mergoum,* and Joel K. Ransom ...

High herbicide levels can be localized on or near seed of acetolactate synthase (ALS) resistant maize (Zea mays). The magnesium salt of imazapyr was optimal for seed dressings (drenching, priming, and coating), for preventing field damage from parasitic Striga hermonthica (witchweed) in three seasons. Striga emerged on untreated maize from 6 to 12 weeks after planting. There was almost no

ABSTRACT Crop rotations with crops that are non-hosts of Striga were evaluated to reduce the Striga seed bank in the soil and increase farm productivity. Field experiments were conducted at two sites in western Kenya from 1996 to 1998 to study the effect of eight different crop rotations on Striga populations, Striga seed bank in the soil, maize yields and overall productivity of these cropping systems under low-input rainfed field conditions. A variety of crops, such as peanut, soybean, sunflower, pigeon pea showed greater economic potential than maize. The productivity of the best rotation under low soil fertility conditions was five times greater than maize mono-cropping. All crop rotation treatments reduced Striga seed numbers in the soil. Less Striga emerged if maize was planted after a two- season rotation that included pigeon pea. Crop rotation is probably one of the most effective ways to reduce Striga infestations and increase maize yields and income considering the limited resource base of small-scale subsistence farmers in sub-Saharan Africa.

Striga hermonthica is endemic in the semi-arid and semi-humid areas of Sub-Sahara Africa. This plant parasite reduces crop yields of maize and sorghum, the major staple food source of the region. Presently, there are no Striga-resistant maize varieties commercially available in Western Kenya. Striga resistant or tolerant maize would form an important part of an integrated control approach. To determine

Intercropping maize was evaluated as a means to reduce Striga emergence and survival and improve overall farm productivity. Field experiments were conducted at two sites in western Kenya from 1996 to 1999 to study the effect of eight different intercrops on Striga populations and crop yield. Factors studied included relay or simultaneous planting of maize or intercrops, ridge and flat

ABSTRACT Over the last 40 years, grain yield of hard red spring wheat (HRSW) (Triticum aestivum L.) has increased dramatically in North Dakota and neighboring regions. This yield increase has caused some concern that recent higher yielding cultivars might be released at the expense of quality performance. A two-year study was initiated in 2004 to examine the changes in quality performance of HRSW cultivars released by North Dakota State University (NDSU) over the past 40 years. The experiment was conducted in North Dakota at three and two sites in 2004 and 2005, respectively. The study included 33 HRSW genotypes laid out in a randomized complete-block design with four replicates. Grain protein content, flour-extraction yield, mixograin score, Falling Number, glutograph scores, water absorption, dough character score, and loaf volumes did not vary significantly with year of release. Linear regression of cultivar means on year of release showed an annual increase in crumb color score of 0.4%/yr since 1968. Grain volume weight showed a significant and positive correlation with crumb color score (r = 0.62, P < 0.01). Given the yield increase achieved over the past 40 years, the data in this study suggest an increase in grain protein yield per hectare with no decline in breadmaking quality.

The research of JG and EAH on parasitic weed control is supported by grant HNE-0158-G-00-3060-0 from the trilateral US–Israel–Egypt US Agency for International Development (AID) program. JKR's research is supported by the Canadian International Development ...

... Dr. Joel Ransom served as the ad-hoc technical editor for this special section of Agronomy Journal, which features papers from the symposium “Residue Removal and Soil Quality—Findings from Long-Term Research Plots,” organized by Dr. Russell Karow for the ... Almeida,áP ...

ABSTRACT erefore, ABSTRACT Hard red spring wheat (HRSW) (Triticum aestivum L.) grain yield is comprised of the combined production of the main stem and tiller spikes. Experiments were conducted under dryland (Casselton, ND) and irrigated (Carrington, ND) conditions from 2003 to 2005 to determine tiller development and the relative contribution of main and tiller wheat spikes to fi nal grain yield under varying cultivar, seeding rate (SR), N rate, and N timing. Th e experimental design was a randomized complete block design (RCBD) with a split-split plot arrangement with four replicates. Treatments consisted of a factorial combination of HRSW cul- tivars (Alsen and Granite), SR (2.9 and 4.2 million seeds ha-1), N levels (140 and 224 kg ha-1 for the nonirrigated site; 168 and 280 kg ha-1 for the irrigated site), and N timings (preplant, 2-split, and 3-split). Increased SR signifi cantly increased stand count. Th e lowest SR and N level signifi cantly increased tillers m-2, while the 3-split N timing treatment signifi cantly reduced tillers m-2. Increased N level and SR signifi cantly increased spikes m-2, while the 3-split N treatment signifi cantly reduced spikes m-2. Cultivar, N level, and N timing main eff ects did not infl uence the relative contribution of the main spike and primary tillers (T1, T2, and T3) spikes to grain yield. Increasing the SR increased the proportion of yield from the main spike and decreased the proportion from the T2 spike. For environments where fewer tillers are desired, SR appears to have the largest impact on tiller numbers without negatively infl uencing yield.

ABSTRACT Seeding rate,N level,and N application timing arekeymanagement factors for spring wheat (Triticum aestivum L.) production in North Dakota. Experiments were conducted under dryland (Casselton, ND) andirrigated (Carrington, ND) conditions in 2003 to 2005 to determine the optimum combination of seeding rate and N management to maximize yield of hard red spring wheat (HRSW). Treatments con- sistedof afactorial combination of HRSWgenotypes('Briggs', 'Alsen', 'Granite', and ND 740), seeding rates (2.9 and 4.2 million seeds ha21), N levels (140 and 224 kg ha21 for the dryland site; 168 and 280 kg ha21 for the irrigated site), and N application timing (preplant, two-split, and three-split). Nitrogen level, N timing, and seeding rate showed no significant effect on grain yield across environments. However, genotype significantly influenced grain yield. Increasing seeding rate failedtoincreasegrainyieldofthethreecultivars,butND740wasmost productive at the lowest seeding rate. Increasing the level of N sig- nificantly increased grain protein content (GPC) over all environ- ments. Grain volume weight (GVW) and thousand kernel weight (TKW) decreased with increasing N level and were influenced by genotype. Increased seeding rate significantly increased plant stand and tiller number while increasing N levels significantly increased head count. These data indicate that although genotype was the primary factor in determining grain yield, GPC, and agronomic traits, individ- ual genotypes responded differently to varying seeding rates and N management practices.

Maize (Zea mays L.) is the most important cereal crop in the hills of Nepal, where the grain is used for human consumption and the stover for animal fodder. Maize farms are small, and population pressure necessitates the intensification of existing farming systems. Maize research directed at developing technologies for maize production began in Nepal in 1965. In 2000, a