Top Crop Manager

Features Agronomy Storage
Storage issues ‘bugging’ growers

New and emerging pests on the rise.

November 14, 2007
By Top Crop Manager


Storing grains has always been a challenge, but with more growers opting to
store more of their corn and wheat, they should not forget about the threat
of spoilage from stored grain insects.

According to Dr. Art Schaafsma, with the Ridgetown Campus of the University
of Guelph, both the spectrum and the severity of pest infestations in on-farm
storage bins are on the rise. At present, Indian meal moth and rusty grain beetle
are the main culprits in southern Ontario. As the climate seems to be warming,
pests like the lesser grain borer are tending to move farther north and east
and may enter Ontario. Grain lice and grain mites are becoming more of a nuisance,
but not a major economic threat.

The more pressing concern is in dealing with the current pest challenges, including
Indian meal moth and rusty grain beetle. These two trade positions as number
one and two pests in Ontario, and feed on good grain. Finding one insect can
prompt an elevator to reject an entire load of wheat or corn. "One of the
things that we don't like about it is that it spins a web," says Schaafsma,
referring to the Indian meal moth. "It gets to its last stage and looks
for a place to pupate and spins webbing, and you can have the top of the grain
pile sewn together with webbing to about 10 to 12 inches. In a grain bin, it's
an awful mess because grain falls from the top into the auger while unloading
and the auger will plug."


Other minor pests feed on either the bran and germ of cracked grain or grain
dust. "But there's a whole host of insects that will go after grain that's
in poor condition," notes Schaafsma. All the more reason why proper storage
of wheat is becoming such a huge issue. "The key is keeping things clean,
everything has to be well cleaned: bins, especially with those aerated floors,
grain handling and harvest equipment, and spills."

Bins and the grain should be treated with Protect-It after they are cleaned
and during loading. Products containing malathion are no longer recommended
because meal moths are resistant to malathion. Protect-It, on the other hand,
is made primarily of diatomaceous earth and scratches the waxy coating of an
insect, causing dehydration and death.

Monitoring and early detection are key. Heat generation is one sign that infestation
is occurring, and indicates the problem has progressed too far. At that point,
preventative measures like Protect-It on its own are useless. Infestations must
be detected before any heating occurs. One way to monitor important insects
is to use a grain probe insect trap. When infestation is first noticed, rescue
measures, such as turning grain and treating it with Protect-It or using a fumigant,
are required. -30-