Dry and cool or fumigate best way for clean store?
By Andrew Swallow
RISING grain rejections due to insect infestation suggest some growers are still failing to get to grips with storage techniques, experts warned at Grain 99.
But opinion was divided over best practice.
Drying and cooling should be sufficient to prevent infestation in all stores, advised Central Science Laboratory grain storage specialist David Armitage, co-author of the new HGCA-funded Grain Storage Guide.
But for many farms facing the practical hassles of establishing autumn crops, post-harvest fumigation was more advisable, suggested Igrox grain storage business manager Ian Clayton-Bailey.
"If drying and cooling were sufficient we would not have an infestation problem. But we have been getting four or five calls a day to deal with rejected loads or infested stores this autumn."
Most problems arise where ventilation is inadequate, either due to the design of the store or growers inability to dedicate time to monitoring grain and air temperature and control fans accordingly. But even with modern stores and automated fan systems problems can arise if there is a lack of cold weather, he noted.
By contrast, phosphine fumigation kills all grain pests. Cost is about £1/t for a 1000t bulk store, and there is no problem of organo-phosphate residues. "There is no problem with acceptability."
The service is guaranteed to keep grain pest free for 12 months. But growers should still monitor grain with temperature probes and pitfall traps. "We want them to prove us wrong," said Mr Clayton-Bailey.
But phosphine offers no lasting protection and is expensive compared with cooling and drying, stressed Mr Armitage. "We are talking p/t for cooling, 5-10p, even less if you use night tariffs."
Growers should not be concerned about blowing moist air through grain in the UK climate, he added. Heat from fans lowers the relative humidity of the air, and cool air carries little moisture anyway. *
• Infestations widespread.
• Prevention beats cure.
• Cooling cheap but management intensive
• Prophylactic gas where ventilation limited?
The Grain Storage Guide uses HGCA-funded research results to provide detailed advice to help growers improve on-farm storage. The 32p colour booklet is available free to levy payers from the HGCA (020-7520 3945).