Leaffooted bug (LFB) represents an infrequent but significant pest in almonds. However, increasingly warmer falls and winters could be contributing to more ideal overwintering conditions for this pest.
Leaffooted bug pressure is directly tied to overwintering populations. 2006 was the most recent major-outbreak year, and was preceded by two mild winters that lacked significant hard frost, which would have killed off overwintering adults. This allowed adult LFBs to survive the winter in aggregations outside of orchards, and then move into almonds at full strength after leafout in March. If the winter of 2015–16 does not provide significant hard frost, LFB aggregations are likely to begin moving into almond orchards in March. Recent controlled studies by UC IPM advisor Dr. Kris Tollerup show there is significant mortality at 27°F for a period of six hours. As before, Almond Board will provide advisories on the status of aggregations.
Monitor in March
In order to determine if LFB is a problem in your orchard, the best line of defense is a good offense. Early monitoring for LFB is best performed by poling suspected orchards in March once trees have leafed out and nut development has begun. The LFB is a particularly loud flyer and large bug, so it can easily be observed flying away when disturbed. Finding adult bugs is the best indication that a problem may arise, and an 8-foot pole can be used to strike the upper limbs while walking through orchards. Walking the orchard and monitoring for gummosis is a more practical approach; however, by the time that gummosis is observed, feeding and damage have already occurred. If gummosis is observed, a cross section of the nut should be examined to look for puncture marks from LFB’s mouthparts. This will confirm that the gummosis is not due to diseases such as bacterial spot or physiological reasons. The easiest method to monitor for LFB presence is to look for aborted nuts on the orchard floor. However, gummosis and nut drop typically occur seven to 10 days after feeding has occurred, by which point LFBs have likely dispersed or moved on to another block.
Varietal Preference
Research by David Haviland, UC Cooperative Extension entomology farm advisor, Kern County, shows that leaffooted bug exhibits varietal preference for Fritz, followed by Aldrich and Sonora. Recent work by UC Merced entomologist Dr. Andrea Joyce substantiates that almonds are most susceptible to drop caused by LFB feeding from late March to mid-April. Detailed information about leaffooted bug, its life cycle, damage and management, is available online. For more information about LFB management in your area, contact your local farm advisor.
