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Bt Calculator
The 1st Generation
1st generation European Corn Borer (ECB) larvae drill holes in
the leaves when rolled up in the whorl. When the leaves unroll,
the affect is a shotgun pattern on the leaves. As the larvae mature,
they tunnel into the stalk and interupt the nutrient flow - kind
of like sipping through a straw with holes in it. Since the 1st
generation ECB cause damage in both the vegetative and grain fill
stages of the plant, we give them a higher yield loss factor. An
average of one 1st generation ECB larvae per plant reduces grain
yeild by 5%.
What to plug in:
Low = 10-30% plants infested
Moderate = 40-60% plants infested
High = 70-100% plants infested
The 2nd Generation
2nd generation ECB attack corn plants after pollination and affect
yields by reducing the amount of dry matter accumulation in the grain.
The estimated yield loss reflects ONLY the reduction of grain-fill and
does not include yield loss due to stalk breakage and ear droppage.
An average of one 2nd generation ECB larvae per plant reduces grain
yield by 3%. ( This count may be derived from the number of egg masses
below the ear shoot. Entomologists estimate that 4 larvae develop from
any one egg mass, and only one of those will survive to maturity.)
What to plug in:
Low = less than 1 egg mass per plant average
Moderate = 1 egg mass per plant average
High = more than 1 egg mass per plant average
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