Evaluation of Organic Materials for Modified Atmosphere Production for Maize Weevil Control in Stored Maize

Abstract

Experiments were conducted in a laboratory and in storage structures in the field between 2008 - 2009, to assess the amount o f the COj and 0 : produced and the modified atmospheres produced (gas mixtures) as protectants o f maize grains against the maize
weevil fSitophilus zeamais MotschJ. The production of modified atmospheres (MAs) by composting fresh cow dung, chopped fresh sugarcane and chopped dry maize stubble each wetted at 60% moisture content was studied. The MAs were produced in plastic
cans (bio-generators). The measurement o f the MAs produced using Riken Infrared Gas Analyzer. Model R1-550A for CO: and portable oxygen meter for 0 : indicated that the highest CO^ levels were produced in fresh cow dung (25%) and fresh sugarcane (23%) following 4Shr incubation period. These substrates gave the tower 0 : content (3.5% and 3.7%), respectively) compared to the dry maize stubble which resulted in lower CO: level (9%) and the highest 0 : content (I9%>). The efficacy o f the MAs produced by these substrates was also studied in simulated storage structures in the field by letting the produced gas mixtures to storage structures containing 3 quintals o f weevil susceptible BH-540 maize variety. Analysis o f variances showed that application o f modified atmosphere to the maize grains stored in airtight storage structures can effectively control maize weevils. Significantly (p<0.0l) higher mean numbers o f weevils mortality and lower mean number and weight o f damaged grains and weight losses were recorded in maize grains treated with Quickphose (fumigant standard check) and modified atmospheres from fresh cow dung and fresh sugarcane. The gas produced from the digestion o f fresh cow dung and fresh sugar cane significantly (p<().OI) reduced the
progress o f maize weevils infestation. Germination test did not show any variation among the treatments. The result o f this study showed that the gas from biological digestion of fresh cow dung and chopped sugar cane can be used as control option for maize storage pest in airtight storages. However, rate and frequency o f application and economic feasibility should be studied before commercial application o f the technique