The invasive fall armyworm (FAW) is threatening maize production and the livelihoods of millions of smallholder farmers in the newly invaded areas in Africa and Asia. To control this new key pest and to overcome health, environmental, and resistance problems related to the indiscriminate use of insecticides, effective and sustainable alternative pest control approaches are needed. Here, we report on field trials that tested maltodextrin, neem-based products, ash, and soil, as well as the locally produced alata samina soap, in the Upper West and Greater Accra regions, Ghana. Significant reductions of larval numbers and crop damage, together with increased yields, were mostly achieved by applying the insecticide emamectin benzoate, which was considered the positive control in this set of trials. However, high efficiency and cost–benefit ratios were also achieved with two neem-based products. Maltodextrin was only efficient at one of the two sites, with a clear dose-dependent effect, while the higher dosage was nearly as effective as emamectin benzoate. Due to its relatively high product cost, maltodextrin is generally less cost-efficient. Ash and soil, as well as alata samina soap treatments, did not efficiently reduce FAW larval numbers or crop damage at the dosages tested; thus, they also did not significantly increase maize yields.

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Enhancing water use efficiencies of rain-fed maize is a requirement for sustainable maize production, particularly in areas prone to low/ drought and erratic rainfall patterns. This study was conducted to assess the relationship between total biomass/grain yield and water use efficiencies of three maize cultivars (Golden Crystal, Mamaba and Obatanpa) grown under rain-fed conditions in a coastal savannah agroecological environment of Ghana. Results of the study showed that a unified linear model, WUE TDM = 0.03 TDM with R 2 = 0.765 and P ≤ 0.001, described adequately the relation between water use efficiency and total biomass (dry matter), which is applicable for the three maize cultivars for both the major and minor cropping seasons. A linear model could only, however, describe adequately well the relation between WUE GY and GY for the major (WUE GY = 0.001 GY -0.67; R 2 = 0.996; P ≤ 0.001) and minor (WUE GY = 0.002 GY + 0.289; R 2 = 0.992; P ≤ 0.001) cropping seasons for all the maize cultivars. The linear models developed for the maize cultivars, relating WUE GY to GY, are specific to each of the crop growing seasons, indicating that seasonal rainfall impacts significantly on harvest index of the maize cultivars but differently in each of the crop growing seasons as a results of differences in seasonal rainfall. However, the models could be used to estimate water use efficiencies of each of the three maize cultivars given the appropriate TDM and GY as inputs for the environment under which the study was conducted.

A field experiment was carried out in a coastal savannah agro-ecological zone of Ghana to assess the dynamics of stored soil water and actual evapotranspiration (AET) of three maize genotypes (Obatanpa, Mamaba, and Golden Crystal) grown under rainfed conditions. Access tubes were installed to a depth of 120 cm for soil water content monitoring using a neutron probe meter. The soil water balance model of plant root zone was used to estimate AET at different crop growth stages. On average, the rate of AET for Obatanpa, Mamaba, and Golden Crystal maize genotypes were estimated as 4.32, 4.46, and 3.72 mm·day^–1, respectively, for the major cropping season as against corresponding values of 3.88, 4.00 and 3.72 mm day^–1 for the minor cropping season. Mamaba had higher values of AET from 42 DAE (days after emergence) to 84 DAE during the minor cropping season while it had low AET values during the major cropping season. The positive balance in stored soil water in the root zone of Obatanpa was the highest from 42 DAE to 84 DAE followed by Mamaba and Golden Crystal during the major cropping season. Mamaba, on the other hand, had the highest AET from 70 DAE to 84 DAE. Obatanpa used 55.6% of stored soil water for AET, which was the highest among the maize genotypes during the major cropping season. Golden Crystal and Mamaba followed with 53.3% and 51.5%. For the minor cropping season, 48.5% of stored soil water was used by Mamaba for AET, followed by Obatanpa, (46.4%) and Golden Crystal (43.2%). A strong positive significant (p ≤ 0.05) linear correlation existed between AET and precipitation with the coefficient of determination (R²) being 69.2 for Obatanpa, 88.5 for Mamaba and 82.8 for Golden Crystal for the major cropping season. Higher R² values (98.0, for Obatanpa, 94.1 for Mamaba and 98.9 for Golden Crystal) were, however, obtained for the minor cropping season. Additionally, a strong linear relationship was found between AET and precipitation, suggesting the need to formulate strategies for enhancing effective use of precipitation in sustained rainfed maize production

The destructive nature of maize fall armyworm has triggered the importation of plenty of plant protection products onto the Ghanaian agrochemical marketplace. These imported chemicals sold at market places sometimes are unregistered for use in the Ghanaian environment. Thus, some importers do not do due diligence in testing the chemical agronomically to ascertain its mode of action and also being not harmful to beneficial insect species in the Ghanaian environment. It was in this view that three Ampligo concentrations or rates (0 ml/ha, 200 ml/ha, and 240 ml/ha) were tested against FAW on maize that were sown at a spacing of 60 cm × 60 cm. Treatments applied to maize were arranged in a randomised complete block design and replicated three times. Ampligo rates caused a very significant ( p  < 0.05) reduction in FAW at 21 and 28 days after maize emergence. The damage to maize leaf on treated maize plot was significantly ( p  < 0.05) different from that on the untreated. Thus, damage of FAW was more visible on maize leaves on control plots compared to the treated ones. A significantly ( p  < 0.05) positive correlation existed between damage rating and FAW number. Furthermore, the Ampligo rates correlated negatively to FAW density at p  = 0.014 at 21 days after emergence. Also, FAW infestation did not impact maize grain yield. The study, therefore, concluded that Ampligo pesticide falls in low-risk plant protection product category with a very potent active ingredient that reduces FAW populations. We recommend that Ampligo should be applied between 14 and 21 days after emergence; two applications at one-week interval at 200 ml/ha are sufficient to sustain maize for the whole cropping season.

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