Pest Control Strategies for Pecan by juanagui

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									Pest Control Strategies
for Northern Pecans
William Reid
Extension Specialist, Nut Crops
Pecan Experiment Field
Kansas State University


    There are many insects and diseases that can
injury pecan trees and the nuts they produce but
only a few cause significant damage. Pecan
producers need to learn how to identify
common pest problems and determine if and
when those pests need to be controlled. These
recommendations are intended for pecan
producers in Kansas, Missouri, and Illinois.

Primary Pests
    Two insects and one disease make up the
primary pest complex that growers must deal
with on an annual basis. Pesticides                       Pecan weevil adults (pictured above) emerge
recommended for use in controlling pecan             from the soil starting in early August and
insect pests are given in Table 1.                   continue emerging until early September.
                                                     Female weevils bore through the shuck and
                                                     shell of a nut to lay 5-7 eggs. These eggs hatch
                                                     into legless larvae which completely devour the
                                                     kernel of the nut. Left untreated, pecan weevil
                                                     can completely destroy a pecan crop. Growers
                                                     should install trunk-mounted weevil traps
                                                     (pictured below) to determine peak adult
                                                     emergence periods and apply an insecticide to
                                                     kill adults before they can lay eggs.



    Pecan nut casebearer larvae attack small
nutlets shortly after pollination (pictured above)
and can quickly destroy and entire cluster of
nuts. Growers should develop a regular scouting
program for pecan nut casebearer starting the
4th week in May. An insecticide should be
applied when 2% of clusters are damaged.
                                                    female flowers. Leaf phylloxerans create smaller
                                                    galls on the leaf blades and can cause early
                                                    defoliation. Once growers discover phylloxera
                                                    galls in their orchards it is too large to control
                                                    the insect during the current season. Growers
                                                    need to mark phylloxera infested trees then treat
                                                    those marked trees the following spring during
                                                    bud break. Timing for control of these two
                                                    species is slightly different. To control stem
                                                    phylloxera, spray at inner scale split or when the
                                                    first bit of new green tissue starts to emerge. To
                                                    control leaf phylloxera, spray when the first leaf
                                                    has burst from the expanding bud.

    Pecan scab (pictured above) is the most             Hickory shuckworm populations are often
serious disease of pecan and can infect both        kept in check by insecticide treatments aimed at
leaves and nuts. Scab infected leaves will drop     controlling pecan weevil. However, if pecan
off the tree prematurely, while a scab infection    weevil is not a problem in your orchard, hickory
on the shuck of pecan nuts will reduce nut size,    shuck at build up to large populations and cause
inhibit kernel filling, and prevent proper shuck    nut drop in July (2nd summer generation) and
opening. If scab has been a problem in your         reduce kernel fill in August (3rd summer
orchard, a preventive schedule of fungicide         generation). Growers should monitor their
applications will prevent economic losses.          orchards for signs of hickory shuckworm
Recommended fungicides are listed in Table 2        damage then plan on making insecticide
while a weather based schedule for scab control     treatments the following summer if damage
in given in Table 3.                                begins to increase dramatically.

                                                        Fall Webworm and Walnut Caterpillar are
Secondary Pests                                     two species of caterpillars that feed in large
                                                    colonies and can defoliate pecans. The fall
    Several pecan insects fall into a category of   webworm spins a dirty white web over the
secondary pests. These insects should be            colony while the walnut caterpillar feeds
controlled on “as-needed” basis. The key to         without a protective web. Growers should scout
keeping secondary pests from become primary         for these insects and apply an insecticide only if
problems is to follow a strict orchard              they find more than 5 colonies per acre. Each
monitoring program.                                 insect has two generations per year. New
                                                    colonies appear in mid-July and again in late-
     Two species of phylloxera can create galls     August.
on pecan trees. Stem phylloxerans form large
galls on new stems and leaf mid-ribs distorting
twig growth and inhibiting the initiation of
Table 1. Recommendations for insect control


Insect Pest                Timing                 Pesticide         Rate/acre
Stem Phylloxera            Inner scale split      Asana XL ®        4.8 -14.5 oz.
                                                  Lorsban 4E ® or   2.0 - 4.0 pts.
                                                  Nufos 4E ®
                                                  Provado 1.6F      3.5 - 7.0 oz.
                                                  Warrior ®         2.56 - 5.12 oz.
Leaf Phylloxera            Leaf burst             Asana XL ®        4.8 -14.5 oz.
                                                  Lorsban 4E ® or   2.0 - 4.0 pts.
                                                  Nufos 4E ®
                                                  Provado 1.6F      3.5 - 7.0 oz.
                                                  Warrior ®         2.56 - 5.12 oz.
Pecan Nut Casebearer       2% cluster damage      Ammo 2.5 EC ®     3.0 - 5.0 oz.
                                                  Asana XL ®        4.8 -14.5 oz.
                                                  Confirm 2F        8 - 16 oz.
                                                  Imidan 70WSB      1.0 - 3.125 lbs.
                                                  Intrepid 2F       8.0 oz.
                                                  Lorsban 4E ® or   1.5.0 - 4.0 pts.
                                                  Nufos 4E ®
                                                  Spintor 25C       4 -10 oz.
                                                  Warrior ®         2.56 - 5.12 oz.
Hickory Shuckworm          July 5 - July 14       Ammo 2.5 EC ®     3.0 - 5.0 oz.
                                                  Asana XL ®        4.8 -14.5 oz.
                                                  Confirm 2F        8 - 16 oz.
                                                  Imidan 70WSB      1.0 - 3.125 lbs.
                                                  Intrepid 2F       8.0 oz.
                                                  Lorsban 4E ® or   1.5.0 - 4.0 pts.
                                                  Nufos 4E ®
                                                  Spintor 25C       4 -10 oz.
                                                  Warrior ®         2.56 - 5.12 oz.
Fall Webworm &             When colonies appear   Ammo 2.5 EC ®     3.0 - 5.0 oz.
Walnut Caterpillar                                Asana XL ®        4.8 -14.5 oz.
                                                  Confirm 2F        8 - 16 oz.
                                                  Imidan 70WSB      1.0 - 3.125 lbs.
                                                  Intrepid 2F       4.0 - 8.0 oz.
                                                  Lorsban 4E ® or   1.5.0 - 4.0 pts.
                                                  Nufos 4E ®
Pecan Weevil               In August, based on    Imidan 70WSB      1.0 - 3.125 lbs.
                           trap catch data.       Sevin 80S         2.5 - 6.25 lbs.
                                                  Warrior ®         2.56 - 5.12 oz.
® = restricted use pesticide
Table 2. Recommendations for disease control


Disease                        Timing                 Pesticide                Rate/acre
Pecan Scab                     Post pollination       Abound                   9.2 - 12.3 oz.
                                                      Orbit                    4 - 6 oz.
                                                      Enable                   8 oz.
                                                      Flint                    2 - 4 oz.
                                                      Headline                 6 - 7 oz.
                                                      Pristine                 10.5 - 14.5 oz.
                                                      Sovran                   3.2 - 4.8 oz
                                                      Stratego                 10 oz
                                                      Super-Tin 80WP ®         5.0 - 7.5 oz.
                               Additional             Abound                   9.2 - 12.3 oz.
                               applications at 2      Orbit                    4 - 6 oz.
                               week intervals         Flint                    2 - 4 oz.
                               based on weather       Headline                 6 - 7 oz.
                               conditions             Pristine                 10.5 - 14.5 oz.
                                                      Sovran                   3.2 - 4.8 oz
                                                      Stratego                 10 oz
                                                      Super-Tin 80WP ®         5.0 - 7.5 oz.
® = restricted use pesticide



Table 3. A weather based method for timing pecan scab control measures


Fungicide application          Timing

First cover                    immediately after pollination
Second cover
                               14 days after first cover spray, if:

                               (1) No rain has occurred, but the 5 day forecast for rain is >
                               50%, OR
                               (2) One rain event has occurred, and the 5 day forecast for
                               rain is >40%, OR
                               (3) Two rain events have occurred, and the 5 day forecast for
                               rain id >20%, OR

                               (4) Immediately after three rain fall events

Third cover                    Begin weather based rule 14 days after second cover.

								
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