How does maturity group affect ASR infection and severity?
One maturity group is no more or no less susceptible to the disease than another. Since ASR cannot overwinter in Virginia and must move here from the south, latermaturity groups are more likely to experience exposure to ASR and/or higher inoculum levels than early-maturity groups. Early-maturing cultivars will enter into the reproductive stages sooner; therefore these cultivars are likely to be in later stages of development when ASR arrives. Risk of yield loss progressively decreases as soybeans move past the late-pod development (R4) stage. Therefore, less yield loss would occur for a maturity group III in the late-seed (R6) stage, than would occur for a maturity group IV in the early-seed (R5) stage. Likewise, a maturity group IV in the early-seed (R5) stage would incur less yield loss than a maturity group III in the late-pod (R4) stage. Later-maturity groups are also more likely to require multiple fungicide applications. Early-maturity groups will reach “safe” development stages
