Control of charcoal rot in sprouting-grade mungbean seed is going to be possible only if everyone — including growers, buyers, sprouters and seed-testing laboratories — cooperates every step of the way, according to new research by the Queensland Department of Primary Industries.
Project leader Malcolm Ryley says that with over 35 per cent of seed samples from commercial growers testing positive for charcoal rot in the 1995-96 and 1996-97 crops, there is an urgent need to find ways of controlling the fungus.
"I expect that the industry will be unable to completely eliminate charcoal rot infection from mungbean seed. The best we can really hope for is to reduce infection levels and the number of charcoal rot-infected seed lots."
Stress leads to rot
The research team identified a potential problem using herbicides to defoliate plants before harvesting. "It seems that the fungus can spread from the stem and leaves to the pods when the plants are stressed in this way. Growers of sprouting-grade mungbeans need to take this evidence into, account before using defoliants," said Dr Ryley.
What to do?
Although there is as yet no total-control strategy, the following steps can help to minimise the number of infected seed-lots: