Wednesday, November 27, 2019

The price for not controlling pecan scab

     2019 will be a year remembered in our area for its unusually frequent rain-showers. It rained all summer long and that weather pattern has continued into pecan harvest season. Only a fraction of the native pecan groves that grow along the Neosho river have been harvested. However, with much of the crop still hanging on the trees, I had the opportunity to photograft some of this year's native nuts (photo above,  right).   
    The first thing I noticed was that many of the hulls have not opened up, or if they had, opening was incomplete.
  Looking over the nuts on a single tree, I found entire clusters of stick-tights (photo at left). The shucks of these nuts never opened up because they were severely infected by pecan scab during our wet summer months.
   On the same tree, I could find nut clusters that had open shucks. However, even the shucks that had opened showed signs of scab infection (to a lesser extent than stick-tight nuts). To illustrate the impact of scab on native pecan yield, I collected nuts from open shucks and nuts from stick-tights.
    The photo above shows the nuts (top) and kernels (bottom) of the pecans I collected from open shucks as compared to stick-tights. On average the nuts peeled out of stick-tights were smaller than those pulled from open shucks. The kernels of open shucked nuts were well filled and plump. Kernels pulled from stick-tight nuts were often shriveled and dark.
   Commercial pecan growers always discard stick-tight nuts during the nut cleaning process. So in effect, scab causes total economic loss from heavily infected pecans. This year, native pecans required a strong fungicide program to prevent major crop losses. Our native trees set a heavy crop in 2019, but with the widespread outbreak of pecan scab, less than 50% of those nuts will be marketable.