elast bronzing

Many growers are observing some bronzing on the underside of their leaves at this point in the season. You can have bronzing from sunburn when the foliage flops over from the weight of the crop load and exposes the underside to the sun. We see plenty of that out there right now but we also see bronzing from environmental conditions (hot, dry weather) and fungicide applications. All fungicides can cause a bit of bronzing under the right conditions; however, Elast often results in some of the more noticeable bronzing, particularly where multiple applications have been made.  But, what are the overall effects of this bronzing?

The leaves in the photo above are from a “bronzed” ‘Desirable’ sprayed 4 to 5 times with Elast (on the left) and a Cape Fear leaf on the right.  Notice the subtle bronzing of the ‘Desirable’ leaf.  Dr. Bruce Wood published a study in 2000 investigating the effects of pecan foliage bronzing on the tree and nut crop. His results showed reduced photosynthesis with bronzing and also slightly reduced kernel weight and % kernel when bronzing occurred early in the season (July). Bronzing later in the season seemed to have no effect.

So, does this mean you should not use Elast or other fungicides that may cause bronzing? No, the benefit you get from Elast and the other fungicides in scab control far outweigh any minor losses you may observe from the bronzing of the underside of pecan leaves. Elast is one of the best fungicides available for nut scab and is a key component of a good fungicide program for scab on susceptible cultivars.

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