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Pecan Phylloxera

This week we have had an influx of reported issues on pecan trees. Please read this excerpt from our Pecan Specialist Lenny Wells:

Leaf Phylloxera

Leaf Phylloxera

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The southern pecan leaf phylloxera is primarily a pest on mature pecan trees, but it can be found on young trees.  Overwintering eggs hatch beginning the first week of April and continue until the first of May.  The newly hatched stem mothers crawl to the expanding leaves where they settle down and begin feeding.  Feeding causes rapidly growing gall tissue which encloses the immature stem mother within a few days.  Stem mothers mature by mid-April at which time they lay eggs within the gall.

Of much greater concern than leaf phylloxera, a separate species, stem phylloxera can be much more damaging. They produce a hard swelling or tumor like galls, one tenth to one inch in diameter on leaves, leafstalks, succulent shoots, catkins, and nuts of new growth.  Heavy infestations can completely destroy an entire nut crop and the accompanying malformed and weakened, infested shoots reduce tree vitality to such an extent that damage may reduce the following year’s production. This is rarely seen in managed orchards but where it does occur it needs attention.

Imidacloprid is a good, inexpensive, systemic choice for phylloxera control. Phylloxera sprays should be applied just after bud break or no later than when the leaves are one-third grown. Once galls are observed it is too late to spray until next year.

Phylloxera increases the likelihood of problems with hickory shuckworm. Shuckworm adults find phylloxera galls a suitable place to lay their eggs. As a result, damage from first-generation shuckworm can be significant in orchards with heavy phylloxera infestations. Therefore, growers will need to treat for shuckworm. Intrepid, Dimilin, or Belt are all good options for shuckworm.

To get up-to-date information on pecan insect pests call the Pecan Hotline at 1-800-851-2847.