1. Sample at least once per week.
2. Sample every fourth tree in every fourth tree row.  Be sure to cover the entire orchard. Location in the orchard and varietal preference may affect population levels of some pests.
3. Sample a minimum of ten terminals (nut clusters) and ten surrounding compound leaves per tree.  Check all compound leaves on each terminal for black aphids.  Sample upper and lower surfaces of compound leaves.
4. Sample representative cultivars.  A map of each orchard with varieties marked is desirable.
5. When pest populations are near treatment levels increase the number of trees checked per orchard and the number of samples per tree as necessary to gain confidence in control decisions.
6. Observe when traveling from tree to tree.  Do not overlook the obvious.

The absolute number of samples and the amount of time required for surveys when pest populations are near treatment levels will be related to monitoring experience. 

Hanging-type blacklight traps (BLTS) can be used to monitor nut casebearer and hickory shuckworm populations,.  At least two BLTS per orchard should be placed by May 1 (for casebearers) or by June 1 (for shuckworms).  Traps should be suspended from a pulley attached to a tree limb about half way up the trees.  They should be 25 - 30 feet off the ground in mature trees. They should only be placed in trees with good nut crop and as far as possible from buildings or other light sources.  Placement of BLTS in trees with a low nut crop or near lighted areas may reduce trap catches.  Traps should be operated 3 nights per week and emptied following each night’s operation.  Trap catches should not be allowed to accumulate for more than one night because of the added difficulty in separating the insects caught.  BLTS are also useful as a supplement to orchard surveys in detecting other moth pests. 

Commercially available pheromone traps can also be used to monitor hickory shuckworm and pecan nut casebearer populations.  Pecan nut casebearer traps have proven very effective.  Establishment instructions and suggested treatment guidelines come with the traps.

Pecan weevils can be sampled with Masonite board traps, (currently recommended), cone cage “Malaise” traps in tree crotches, cone cage ground traps, burlap-bag band traps, sticky-band traps, knock-down sprays, sheet emergence traps, or a combination of methods.  Weevil traps should be placed under and on “indicator trees” known to have heavy weevil infestations. At least 10 trees per orchard should be sampled. 

Thresholds:

A.  Foliar Pests:

1.  Yellow Aphids - “Yellow” aphids (including the yellow pecan aphid and the blackmargined aphid) may be found in the orchard throughout the growing season. They are commonly found on the undersides of leaves.  In Georgia, yellow aphid populations are usually heaviest in April - May and again in late summer and fall. They are more likely to require treatment during these population peaks.  Current suggested treatment levels for yellow aphids are:

Budbreak to July 1 --- Rely on beneficial insects for suppression.
After July 1 --- 20 aphids per compound leaf or heavy honeydew.

Honeydew, a sticky substance excreted by the aphids is rated as:

0 - None
1 - Light - some present on leaflet surfaces
2 - Medium - very obvious on leaflet surfaces (25% coverage of leaflet surface)
3 - Heavy - Leaflets coated, possibly dripping
4 - Heavy with sooty mold

Ratings for other foliar insect pests mentioned are based on the following broad criteria.

0 - None
1 - Light - occasionally seen, no immediate threat
2 - Medium - frequently seen, apt to increase to damaging levels
3 - Heavy - obvious economic damage will occur if not treated
4 - Very Heavy - defoliation or other damage underway

2.  Black Pecan Aphid - Black pecan aphids may be found in orchards as early as April but usually do not reach damaging levels until late summer. They may be found on both sides of pecan foliage.  Their feeding causes bright yellow spots on the leaflets.  The damaged tissue later turns brown and injured leaflets may drop.  Prior to July 1, treat if 25% of terminals have 2 or more black pecan aphids. After July 1, treat if 15% of terminals have 2 or more black aphids.   When scouting for black pecan aphids, all the compound leaves on each terminal should be checked for aphids or fresh injury. It is extremely important to detect slight increases in black pecan aphid populations before damage becomes severe.

3.  Mites - Mites, especially the pecan scorch leaf scorch mite, have a seasonal distribution very similar to the black pecan aphid.  They are not a serious annual pest in all orchards but can cause serious damage when present in high numbers.  Leaves damaged by mites normally have a bronzed or scorched appearance.  Mite damage usually begins along leaflet mid-ribs and spreads outward.  Damage shows up first on low limbs in shaded, interior portions of trees.  After July 1, mites should be controlled when mites and light damage are observed on the foliage of low limbs in 25% or more of the sampled locations.  However, mite populations are often unevenly distributed.  Spot treatments are frequently possible for clumped infestations.

4.  Leafminers - Leafminers, especially the serpentine leafminer, are secondary pests of pecan and are pests of good management.  They most commonly are a serious problem where repeated insecticide applications have decimated their natural parasites without providing leafminer control.  When present, they are normally a problem in late June or early July.  Leafminers should be controlled when there is an average of one mine per leaflet on 5 or more leaflets per compound leaf in 25% of the leaf samples, or when damage is rated medium.

B.  Nut Pests:

1.  Pecan Nut Casebearer - The pecan nut casebearer is a sporadic pest in Georgia. Their most serious damage normally occurs shortly after nuts are set.  Adult moths lay small, flat, whitish eggs on the nuts, normally one egg per cluster (a hand lens may be needed to see the eggs).  Emerging larvae ultimately feed on the nuts.  One larva can destroy all the nuts in a cluster. Infested clusters are easily recognized because the nuts are normally held together by a small silken web containing a dark mass of frass.  Second generation nut casebearers may also occasionally cause significant damage to individual nuts. Treat when 3% of nut clusters are infested with eggs or larvae.  Try to time sprays before more than one nut per cluster is infested. 

2.  Pecan Spittlebugs - Pecan Spittlebugs are also occasional pests of pecan terminals. They are easily recognized by the white, frothy, spittle-like masses which cover the immature stages.  They should be treated when 5% of the nut bearing terminals have spittle masses.

3.  Hickory Shuckworms - Hickory shuckworms are present in pecan orchards throughout most of the season but are not usually found in significant numbers  until June or later.  Prior to shell hardening, the creamy white, brown-headed caterpillars feed inside nuts and cause them to drop. After shell hardening, larvae feed in the pecan shuck, causing it to stick to the shell.  Shuckworms can be sampled adequately only with traps.  Pheromone traps (Scenery Inc., P. O. Box  426, Buckeye, AZ 85326 - 0091) are now available which simplify sampling for shuckworm.  Use the treatment guidelines which come with the pheromone traps to decide when to treat.  If BLTS are used, the treatment guidelines for  shuckworm reads: treat when BLT catches increase for three consecutive trapping periods and when 7 or more moths are caught in any BLT; or, when 4 or more moths are caught in any BLT for 3 consecutive trapping periods.

4.  Pecan Weevils - Pecan weevils emerge from the soil from late July into October in Georgia.  Peak emergence is typically between August 10 and September 20. Adult weevils may cause some feeding damage and nut drop prior to shell hardening, but the most serious damage is done by adult egg laying and larval feeding after shell hardening (gel stage). The grubs can completely destroy the interior of the nut.  When mature, larvae chew a circular hole through the shell, leaving a hollow nut. Potential indicator trees with heavy weevil infestation can often be found by checking some damaged nuts beneath the trees.  Weevil emergence should be sampled with traps.  Masonite board traps, ”Malaise” traps, cone cage traps or a combination of traps and knockdown sprays are preferred.  After kernels gel and shells harden, weevils should be treated when emergence increases and/or following rains during emergence periods.   Treatments should be continued at 7 - 10 day intervals until emergence ceases.  

Checking for Adult Pecan Weevils

Several methods of sampling the emergence of adult pecan weevils have been developed.  These methods can be used to improve the timing of spray applications for weevil control and are also of value in assessing the effectiveness of spray applications and determining the need for additional sprays after mid-September. With any of these methods, the grower should examine trees that have a known history of pecan weevil infestations. Examinations should be made from July 15 to October 15, and even later if weevils are still found.

Traps to Catch Weevils as they Emerge from the Soil

Cone cage traps are commonly used throughout the Southeast to check weevil emergence.  The basic cone design can be constructed from a 7-foot strip of 42-inch width aluminum screen and four 32-inch lengths of lath (Figure 1).  Cut the screen to form a semicircle within a 42-inch radius.

Cone cage traps should be placed under at least 10 trees in each orchard.  There should be three tarps under each quadrant of the tree, placed at a distance of four to 12 feet from the trunk. Traps should be examined at least twice a week for adult pecan weevils. These traps provide more information about adult emergence than about the presence or activity of weevils in trees. 

Similar screen traps, called Malaise-type traps, can be placed in the crotches of trees to sample weevil emergence (Figure 4A).  To construct a malaise-type pecan weevil trap, cut a half circle of aluminum window screen (36 inch diameter) and form it into an upright cone.  The cone will have a height of 32 inches and a basal diameter of 36 inches.  Staple four 1x1x30 inch wood supports to the sides of each cone, 3 inches from the top and 3 inches from the bottom of the cone. Form internal hexagonal vanes from nylon screen or net.  Cut two vanes/trap to the dimensions shown in Figure 4.  Slit one at the top, the other at the bottom, slide them together (at 90^o angles to each other) and fasten by sewing or stapling. When inserted into the cone trap, the vanes will divide the interior of the trap into 4 approximately equal areas. Staple the vanes to the wood supports to hold them in place.  Attach the trap in the largest crotch angle of the tree, usually just above the first large scaffold limb, with wire or staples.  Hook guide wires to the top of each wood support and to a nail in the trunk or scaffold limb of the tree.  Spread out that portion of the

Masonite board traps (Figure 5) can also be used to collect weevils as they emerge.  Four of these traps can be cut from a single sheet of Masonite using the measurements shown in Figure 6.  The vertical splits made every 12 inches (12, 24, 36, 48", etc.) along the long side of the Masonite sheet, as indicated in the diagram, should all be 1/8 inch wide.  Once the triangular trap  panels are cut out, the 1/8" splits are used to slide two panels together to form the trap.  The top (narrow end) of each Masonite trap panel should be shaped

One or two completed traps should be placed under at least 10 whitewashed trees known to have weevil infestations in each orchard.  Each trap can be anchored to the ground by tent stakes or a piece of flexible metal hooked through the holes bored in the panels.  If metal strips are used, they can be nailed to the ground using gutter nails.  Traps should be placed in the herbicide strip or area otherwise free of weeds and grasses.  Trees must be whitewashed for this trap to work effectively.  Emerging weevils apparently are attracted to dark upright structures more than to light-colored structures.   Whitewashing the trees and painting the traps dark makes the traps much more effective.  In fact, if sample trees are not whitewashed, this trap should not be used.  Whitewash should cover the tree trunks well onto the bases of scaffold limbs. 

Whitewash can be mixed as follows: 1) finely ground hydrated lime, also known as slaked lime or calcium hydrate - available from most building-supply stores, 2) Salt - meat salt is cheapest but table salt dissolves easier, 3) Water - for application with high pressure paint sprayer or insecticide spray gun.  Dissolve one pound of salt in 2 gallons of water, add salty water to 10 pounds of lime, mix well.  Screen through a 20 mesh standard wire window screen and stir well before use. This makes 2 1/2 gallons of sprayable whitewash.  Very large trees normally require 1 to 1 1/2 gallons of whitewash for complete coverage to a height of 7 feet.   For use with a paint brush, use the same formula except use only 1 1/2 gallons of water. This will yield 2 gallons of whitewash for brushing. 

(Photos and plans for Masonite board traps supplied by W. L. Tedders.)    

Traps to Collect Adult Weevils that Crawl Up the Trunk

Two kinds of traps, the burlap band and the sticky band, can be used for this purpose.  With either trap, a minimum of 10 trees should be checked in each grove.  Loose bark should be removed from the lower part of the trunk up to the height at which the trap is to be placed.  Weeds and trash should be removed from the soil surface within two feet of the tree trunk. 

The burlap band trap (Figure 9) can be made from fabric obtained by ripping out the seams of burlap bags.  Loosely woven, rough textured burlap should be used.  Tightly circle the tree with a 40 - inch width of burlap that has been folded once to a 20-inch width;  the folded edge should be down.  Fasten the burlap to the tree with a band of wire placed seven inches above the fold.  Staple the folded edge tightly to the tree.  Cut the burlap above the wire into 18-inch flaps and then fold the inside flap of outer layer of burlap down itself.  Allow the remaining panels to drop down over the folded panels.  When you lift the panels to check the traps, some weevils may drop to the ground, but you can easily see these on the cleared soil.  These traps should be examined daily.  Plans for the burlap bag trap were furnished by W. L. Tedders.  

Collecting Adults From the Trees

First, spread harvesting sheets, tarpaulins, or sheets of muslin or plastic on the ground to collect weevils that drop from the trees.  Then spray the canopy of each tree to be sampled with 20 gallons of an emulsion composed of .5 to 1 pint of 60% piperonyl butoxide - 6% pyrethrins emulsifiable concentrate per 100 gallons water.  Less spray can be used if the concentration is increased proportionately.  Although they are slower acting, sprays with a synthetic pyrethroid or carbaryl can also be used for this purpose.  The ground sheets should be left in place, if possible, throughout the period of weevil emergence.  They can be checked following each weevil control spray to gain an idea of the number of weevils still active in the trees.

No specific treatment guidelines are available for disease control decisions.  Since there are no curative treatments for scab or other diseases once infection occurs, preventive fungicide applications must be maintained on pecans.  Scab is rated based on the degree of infection (see Disease Section) .  The rating system has proven valuable in determining the relative abundance of scab, its potential for spread, and in evaluating the effectiveness of scab control practices,.  It is also very helpful in adjusting the time interval between fungicide sprays. Another major benefit of scouting is in detecting diseases other than scab. Diseases such as zonate leaf spot, downy spot, and powdery mildew may not be adequately controlled by normal scab sprays.  Early detection of these sporadic but serious diseases can allow control practices to be altered in time to prevent loss.  Other conditions, such as nutritional deficiencies or toxicities can also be detected early by frequent scouting.