Saturday, June 13, 2020

Pecan Nut Casebearer arrives late

    I've been scouting my orchard every other day for the past 10 days watching for the first signs of pecan nut casebearer activity. After inspecting over 100 nut clusters, I found a single casebearer egg and even one nut damaged by a casebearer larva.
    Pecan nut casebearer eggs are difficult to spot in the field because of their small size. However, when I do find them, they are always placed near the tip of the nut just below one of the four sepals. In the photo at right, the red arrow points to a single white casebearer egg. When the egg hatches, the emerging larva will crawl to the base of the nut and start chewing its way into the nut's interior. 
   The damage caused by casebearer feeding is very distinctive. In the photo at left, the yellow arrow points to a pile of insect frass at the base of a nut. As the larva tunnels into the nut it pushes all its excrement out the entrance hole creating a pile of brown waste between the nut and the peduncle. In addition, the larva ties the nut onto the stem with numerous fine silken threads. This prevents the nut from falling off the tree before the larva can move to other nuts in the cluster. A single casebearer larva will destroy 3 to 4 nuts while completing its life cycle.

  I'll be making a pesticide application aimed at controlling casebearer on Monday June 15. That's 5 days later than my average spray date of June 10th.