Monday, June 28, 2021

Scouting for pecan pests

    Every year I have inspected hundreds of pecan nut clusters in early June to determine the date of first significant nut entry by pecan nut casebearer. Casebearer has been a perennial insect pest that can destroy an entire nut clusters shortly after pollination. However, I have searched all month and could not find a single nut damaged by the feeding of a pecan nut casebearer larva (photo above). In fact, my trees look clean of all insect problems at this point (no webworms or walnut caterpillar)

   As part of my regular scouting routine, I always visit some large native pecan trees in a cemetery just across the road from my home. These trees are never sprayed and provide me with an opportunity to see pests develop unchecked during the growing season.


   This past May was cooler and wetter than normal and by the first week in June I found pecan scab infections on native pecan tree leaves (photo at left).   The black spots that dot the leaflets and leaf rachis seem like a minor infection but theses scab lesions will provide provide enough spores to cover young developing nuts with scab lesions. Scab infection early in the nut expansion phase (late June - early July)has the potential to causes serious yield loss.

    Since last Saturday (26 June 2021),  we have entered an extended rainy period that promises to provide ideal conditions for the spread of pecan scab (rain every day for 6-7 days). In my orchard, I gave up waiting for pecan nut casebearer scab and applied a fungicide for disease control back on June 12th. These trees will need a second fungicide spray as soon as I can get in the field and apply it. I'll spray all my trees, even scab resistant cultivars like Kanza. In the past, I have found that the secondary diseases that cause early defoliation usually get their start during mid summer wet periods. By keeping healthy leaves all season long, I canl ensure a good return crop in 2022.