In Ghana, high postharvest losses, irresponsible use of agro-chemicals and inadequate knowledge of good storage operations have been identified as critical constraints during crop storage. Currently, the Ministry of Food and Agriculture projects up to 10-20% losses across dry cereals and 20 to 40% losses in fruits and vegetables. Insect pests, rodents and grain moulds are identified as the most critical challenges in storing dry cereals.
A myriad of insects broadly described as weevils are the major insect pests encountered in storage. The often common insects pests include: red flour beetle, Tribolium castaneum (Herbst); larger grain borer, Prostephanus truncatus Horn; lesser grain borer, Rhyzopertha dominica F.; maize weevil, Sitophilus zeamais Motschulsky; granary weevil, S. Granaries L., Angoumois grain moth, Sitotroga cerealella (Olivier), and cowpea weevil, Callosobruchus maculatus F.
In most instances, farmers apply a cocktail of pesticides to protect their grain when prolonged storage is envisaged or when insect infestation is noticed during storage. Most farmers acquire storage pesticides from non-accredited input dealers without prior training on appropriate use. Indiscriminate use of common grain protectants viz Actellic Super (pirimiphos methyl), bioresmethrin (pyrethroid), Campha, Wonder 55, and phostoxin (aluminum phosphate) is widely reported.
In this second year of collaborative work, we designed experiments and trainings to address some of these knowledge and technical gaps to manage harvest surpluses. We provided information and demonstrations on integrated pest management and good storage operations to reduce on-farm storage losses. We specifically:
- Out-scaled existing technologies to manage major insect pests during prolonged storage of dry cereal grains and pulses.
- Trained farmers, farmer-based organizations and Agricultural Extension Agents on proper postharvest practices for dry cereal grains and pulses
- The study demonstrated that it is possible to keep postharvest losses down to around 0 to 7% using the two hermitic methods evaluated. However, we still emphasize the critical role of good pre-harvest operations drying, and clean grain prior to storage.
- Overall losses in jute sacs, the common method of storage ranged from 39.5 to 77.2% at 12 months after storage across communities. Losses in the two improved hermetic storage methods ranged from 0.00 to 0.5 % in Northern and 0.1 to 7.6% in the Upper East regions. The treatment effect showed no significant difference between phostoxin and actellic, but the two types of protection were consistently better than the control.
Sun-drying of harvest is a common farmer practice in northern Ghana. In this picture a farmer household dries maize and cowpea (on the house roof). Photo credit: Jonathan Odhong’/IITA
- Postharvest interventions like PICS sacs and plastic drums, with or without grain protectants, should be used in the communities to reduce on-farm storage losses.
A participatory on-farm trial was conducted to compare three storage methods and protectants (Table 1 and 2) on storage losses in maize under farmer storage units. The plastic drums are ordinary containers which are mostly utilized in household water storage. They have an air-tight seal which provide hermitic conditions for grain stored. Two common grain protectants: Actellic Super EC and phostoxin were applied at recommended rates of the manufacturers. Actellic Super EC is a food-grade chemical containing 80 g Pirimiphos-methyl and 15g Permithrin/L as emulsifiable concentrate. Phostoxin is a food-grade fumigant.