How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

Codling moth has a 0.5 to 0.75 inch wingspan. The tip of each forewing has a coppery-tinged, dark brown band that distinguishes codling moth from other moths found in pear orchards. Females lay eggs singly on leaves and on fruit. Eggs are disk-shaped, smaller than a pinhead, and opaque white when first laid. Just before hatching, the black head of the larvae becomes visible. Newly hatched larvae are white with black heads. Mature larvae are 0.5 to 0.75 inch long, pinkish white, with mottled brown heads. Depending on climatic conditions and location in the state, there are two to three generations of codling moth each year. Overwintering moths emerge in two distinct peaks: 1A and 1B. The two flight peaks cause a ripple effect in the second flight, which also has two distinct peaks: 2A and 2B.

DAMAGE

Codling moth has the greatest potential for damage of any pear pest, yet it can be effectively controlled with properly timed treatments. It causes two types of fruit damage: stings and deep entries. Stings are entries where larvae bore into the flesh a short distance before dying. Deep entries occur when larvae penetrate the fruit skin, bore to the core, and feed in the seed cavity. Larvae may enter through the sides, stem end, or calyx (flower) end of the fruit. One or more holes plugged with frass on the fruit's surface is a characteristic sign of codling moth infestation. Calyx entries are difficult to detect without cutting the fruit.

MANAGEMENT
A variety of tools are available for codling moth management, including insecticides, mating disruption, and cultural controls. An IPM program uses a combination of these strategies. Mating disruption is the preferred tool for codling moth control because of its low toxicity to people, natural enemies, and the environment. Mating disruption may need to be supplemented with insecticide sprays, especially during the first few years or in orchards with moderate-to-high codling moth population. Alternate insecticides with different mode of action Group numbers in order to avoid the development of insecticide-resistant populations. Supplement all codling moth management programs with cultural controls.

Biological Control
Alone, natural enemies are not able to keep codling moth populations below economic levels. An important parasite of codling moth is Trichogramma platneri, which parasitizes its eggs.

Cultural Control
Remove host trees in nearby abandoned orchards (apple, pear, and walnut) to destroy reservoirs of codling moth. Also remove props, picking bins, and fruit piles from the orchard. Proper pruning and orchard sprayer calibration will improve spray coverage. An option for small, organic orchards is hand thinning to remove all infested fruit during each generation, before worms leave fruit, and removal of dropped fruit. Trunk banding can also be used to help control population levels.

Organically Acceptable Methods
Organically acceptable tools for the control of codling moth include cultural control in conjunction with mating disruption, and sprays of certain oils, codling moth granulovirus (Cyd-X, etc.), the Entrust formulations of spinosad, and kaolin clay (Surround). Currently for mating disruption, both hand-applied pheromone dispensers and puffers are acceptable, however, sprayable formulations are not. Check with your certifier about the exact status of all materials.

MONITORING AND TREATMENT DECISIONS IN A MATING DISRUPTION ORCHARD

Mating disruption has become the primary method of codling moth control in most pear orchards. In orchards with moderate-to-high populations and/or in the first year of mating disruption, insecticides or other supplemental controls will likely be needed in addition to the mating disruption program. Using mating disruption successively over a number of years can effectively lower the codling moth population so that alternative, reduced-risk chemical treatments can be effectively used to supplement control when needed.

Mating disruption works best in larger, uniform orchards that are relatively square. It is not recommended in orchards that are less than 3 to 5 acres in size. The larger the contiguous block of mating disruption, the more effective it will be. Effectiveness will also decline if there are high levels of mated females flying from neighboring orchards or abandoned trees.

Establishing Biofix and Accumulation of Degree-Days
To determine biofix, hang 1 mg pheromone traps in the orchard in early March in Delta growing areas and late March in north coast and Sierra Foothill orchards. Place traps on the southeast side of the tree, about 6 to 8 feet high, with one trap every 5 acres or at least two traps per orchard. Check traps one to two times a week until biofix is set and once a week thereafter until biofix is confirmed. The first date that moths are consistently found in traps for three consecutive days and sunset temperatures have reached 62°F is the biofix. Replace lures at intervals specified by the manufacturer. For more information, see PHEROMONE TRAPS.

To follow codling moth development and time fruit sampling, begin accumulating degree-days from the spring biofix using a lower threshold of 50°F and an upper threshold of 88°F. (For assistance in calculating degree-days, see "Degree-days ".)

Setting Out Pheromone Dispensers
Pheromones are deployed as either hand-applied dispensers or in an aerosol canister (puffer). Sprayable pheromones are available but not currently recommended because of their very short residual.

Be prepared to place pheromone dispensers in the upper third of the tree canopy at biofix in mid-March to early April. It is important for pheromone products to be hung early enough to disrupt overwintering moths as soon as they emerge. A late pheromone application will require supplemental treatment.

When placing puffers, put them on the inside of the canopy of edge trees or on the outside of trees in the second row. Upwind placement is one puffer every 50 to 65 feet, and downwind placement is one every 100 to 130 feet, or an average of 20 units per quarter mile, or 1 to 2 puffers per acre. Also, place a few puffers towards the middle of the orchard on the upwind side. Check puffers every other week to make sure they are emitting properly.

Pheromone dispensers should be actively releasing pheromone throughout the third flight, which may extend into early September. Multiple applications of pheromone may be needed if earlier applications expire before summer codling moth flights are over. This varies depending on the product used; follow manufacturer's guidelines.

Monitoring with Traps
Monitor pheromone-treated orchards carefully to help assure that mated moths have not moved in from adjacent orchards and that the pheromone is successfully disrupting mating. At biofix deploy the following monitoring traps:

Supercharged (10 mg) pheromone traps. Pheromone traps with supercharged (10 mg) pheromone lures are put in the trees at the same level as the dispensers. Use at least one trap per 5 acres distributed uniformly throughout the orchard and a minimum of 2 traps in small orchards. Check traps weekly and replace lures at the frequency recommended by the manufacturer. These traps serve to assist in calculating degree-days (DD) (see "Spray Timing" below) and monitoring the development of the codling moth population; they also signal when fruit should be monitored. Do not rely completely on traps, however, because fruit damage has been known to occur even when traps have not caught moths.

Supercharged traps do not attract moths from far, so additional traps may be needed in areas that are known hot spots and in areas vulnerable to wind where pheromone concentration is likely to be reduced. Examples include high spots and orchard edges; five to six rows inside the orchard is a good location.

If the supercharged traps consistently catch moths (more than a total of 5 moths/week in 2 consecutive weeks or 10 moths in 1 week in orchards that have hand-applied dispensers), monitor fruit in the surrounding area for eggs or damage to determine if a supplemental treatment is necessary. In orchards where puffers are used, if trap catches appear high (more than 3) or if moths are caught in the same trap for more than 1 week in a row, monitor for eggs to determine if a treatment is necessary.

Regular (1 mg) pheromone traps. An additional monitoring tool in a mating disruption program is the use of pheromone traps with the 1 mg lures to verify the effectiveness of the mating disruption dispensers. Hang these traps at biofix in the trees 6 to 8 feet high. Traps with 1 mg lures can also be used in upwind, border trees (placed in second row trees) to monitor the influx of codling moth. Check traps weekly and replace lures at the frequency recommended by the manufacturer. These traps should not catch moths if the dispensers are working. If moths are caught, check the fruit in the surrounding area. If eggs or damage are found, a supplemental treatment should be employed to prevent further damage.

DA lures. A plant-derived chemical (kairomone) lure has been developed to assist in monitoring codling moth populations. This lure is sold commercially as the "DA" lure and is available alone and in combination with pheromone ("combo lure"). The DA lure has been shown to catch both female and male moths, whereas pheromone lures catch only male moths. The sex of moths caught in traps using the DA lure can be determined by looking at the genitalia at the tip of the abdomen. If the moth is female, the abdomen can be squeezed to eject the bursa pouch to determine if the moth is unmated, mated, or mated more than once. Generally, if the female's abdomen feels hard to the touch, the moth is most likely mated.

The DA lure appears to work best in mating-disrupted pear orchards early in the season. The DA and DA/pheromone combo lure may also be used to assess the success of mating disruption in an orchard. Because these lures are relatively new to the market and there appears to be some variability in these lures from one season to the next, use them in conjunction with standard 10X and 1X pheromone lures in order to become familiar with them.

Fruit Sampling
Fruit damage can occur even when no moths are caught in traps, so always check fruit clusters for damage towards the end of the generation (800–900 DD from biofix) or when moths are being caught in traps. Examine one cluster from the top and one cluster from the bottom of 20 trees in a transect that extends from orchard edge to orchard edge. If any eggs or larval entries are found, plan to treat at 250 DD from the second biofix when the second generation emerges. For information about monitoring other pests at the same time, see SAMPLING DURING FRUIT DEVELOPMENT.

If fruit sampling shows that damage is limited to an orchard border, especially borders that are upwind from the dispensers, adjacent to open areas, or on the upper side of an incline, spot treating six to ten rows along the problem border may be adequate.

Harvest fruit sample. At harvest, assess your IPM program by monitoring fruit in the bins for codling moth damage. Sample 200 fruit per bin from 5 bins per orchard (or per 20-acre block in large orchards) for a total of 1,000 fruit. For more information on this sample, see HARVEST FRUIT SAMPLE. For guidelines on monitoring fruit after harvest, see Postharvest Fruit Sample below.

Supplemental Treatments
If codling moth populations are high, supplement mating disruption with azinphosmethyl (Guthion). If populations are moderate to high, apply chlorantraniliprole (Altacor), spinetoram (Delegate), lambda-cyhalothrin (Warrior) or bifenthrin (Brigade) as a supplemental treatment. If codling moth populations are moderate or in the first year of a mating disruption program, use a supplemental treatment of acetamiprid (Assail), thiacloprid (Calypso), or phosmet (Imidan). For low populations, a reduced risk material such as an IGR (methoxyfenozide-Intrepid) may be sufficient. In organic orchards, if supplemental treatments are needed use spinosad (Entrust), codling moth granulovirus (Cyd-X), and oil. Adding low rates of oil with the supplemental insecticide increases coverage and aid in suppression of mites and pear psylla.

First generation. Monitor with traps to determine if supplemental insecticide treatment is needed for the first peak, the second peak or for both. Depending on trap catches, treatment may be needed at 250 DD after the biofix to catch the moths of the first peak (1A) and/or at 600 to 700 DD from the biofix to suppress the second flight peak (1B) of the overwintering moths. The 600 to 700 DD timing may also coincide with the timing for control of obliquebanded leafroller. The choice of chemical depends on population numbers, insecticide rotation, and other insects to be targeted.

For low populations, applying a supplemental spray to the first generation may not be necessary. Use trap catch information and monitor fruit to determine if a spray is needed.

Second generation. To determine if treatment is needed, careful trap and fruit monitoring is essential. Treat at 200 to 250 DD after the 2nd biofix if the 10 mg traps are still catching moths or if damage appeared in the fruit sample. Keep monitoring traps after treatment. If trap catches exceed the threshold (more than a total of 5 moths in 2 consecutive weeks or 10 moths in 1 week in orchards that have hand-applied dispensers), treat at the "stop drop" application timing. In mating disruption orchards where puffers are used, if any moths are trapped, monitor fruit in the area of the puffer for eggs and treat if they are found.

MONITORING AND TREATMENT DECISIONS IN A CONVENTIONAL ORCHARD

In orchards where codling moth is managed primarily with insecticides, pheromone traps, in conjunction with degree-days and sunset temperatures, are used to determine egg hatch and proper spray timing. When using pheromone traps, keep in mind the many factors, such as tree size, trap density, type of trap, trap placement, brand of pheromone, as well as climatic conditions, that can affect trap counts.

Establishing Biofix
Hang 1 mg pheromone traps in the orchard in early March in Delta growing areas and late March in north coast and Sierra Foothill orchards, on the southeast side of the tree, about 6 to 8 feet high, with one trap every 10 acres and at least two traps per orchard. Service traps one to two times a week until biofix is set and once a week thereafter. The first date that moths are consistently found in traps for three consecutive days and sunset temperatures have reached 62°F is the biofix. Replace lures at intervals specified by the manufacturer.

Spray Timing
Begin accumulating degree-days from the spring biofix using a lower threshold of 50°F and an upper threshold of 88°F. (For assistance in calculating degree-days, see "Degree-days ".)

The most effective spray timing for each generation is outlined below. Codling moth has two and maybe a partial third generation each season in the pear-growing regions of California. Pears are exposed to only one and a half to two and a half generations before harvest. Continue to monitor the generations with traps and accumulate degree-days until mid-September.

First generation egg hatch. Time the first spray to the beginning of egg hatch to kill emerging larvae 250 to 300 DD after the biofix. In most orchards, more than one spray may be necessary to adequately control first generation codling moth, particularly if the orchard has a history of codling moth problems or the population is high. If significant moth catches continue after the first treatment, make a second application at 650 DD for the second peak (1B) of the first generation. If trap catches are low or the weather turns too cool for moth activity, you can delay treatment, but continue to monitor. Adding low rates of oil with the insecticide, except when using azinphosmethyl (Guthion) or granulovirus (Cyd-X), increases coverage and aids in mite and psylla control.

Second generation egg hatch. Near the end of the overwintered generation moth flight, trap catches may not be a reliable guide in determining the need for another spray. Females may have completed egg laying, even though males are still being trapped. When 800 to 900 DD have accumulated from the first biofix, inspect fruit for larval entries and fruit clusters for eggs on leaves, fruit, and cluster bases. Examine one cluster from the top and one cluster from the bottom of 20 trees in a transect that extends from orchard edge to orchard edge. If any eggs or larval entries are found, treat. Infested fruit usually drops from the tree around 1200 DD (early July) and can be monitored on the ground at this point.

Use pheromone trap catches to detect an increase in flight activity between 900–1100 DD from the first biofix, which signals the start of the next moth flight—this is the second biofix. For low moth populations, a single application may be sufficient; make this application when 200 to 250 DD have accumulated from the second biofix. For high moth populations, two treatments are usually necessary. Make the first application at 200 to 250 DD. The 2B peak occurs 600 to 700 DD from the second biofix. In late districts this often occurs right before harvest. If degree-day accumulations indicate a late second generation in late districts and traps continue to catch, treat at the "stop drop" application timing.

Fruit sampling at harvest. At harvest, assess your IPM program by monitoring fruit in the bins for codling moth damage. Sample 200 fruit per bin from 5 bins per orchard (or per 20-acre block) for a total of 1,000 fruit. For more information on this sample, see HARVEST FRUIT SAMPLE.

Third generation egg hatch. A third generation of codling moth eggs does not occur every year in every location. Codling moth larvae normally go into diapause (winter dormant state) around mid-August, but in warm years and warm locations they will have already started pupation before mid-August, and these pupae will soon emerge as adults to produce a third flight. This usually occurs shortly after harvest.

POSTHARVEST FRUIT SAMPLE

Regardless of the IPM program (mating disruption or conventional) used in the orchard, evaluate 300 fruit left on trees after harvest to assess its effectiveness and to assess overwintering population levels. If 1 to 2% of the fruit (3 to 6 fruit) are infested, reevaluate your IPM program for the following year and be prepared to treat at first egg hatch of the overwintering generation. (For more information on sampling at this time, see POSTHARVEST SURVEY).

IMPORTANT LINKS

• Degree-day calculator
• Degree-day table
• Sunset temperatures

PUBLICATION

UC IPM Pest Management Guidelines: Pear
UC ANR Publication 3455
Insects and Mites
L. G. Varela, UC IPM Program, UC Cooperative Extension Sonoma County
R. B. Elkins, UC Cooperative Extension Lake County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
C. Ingels, UC Cooperative Extension Sacramento County
Acknowledgment for contributions to Insects and Mites:
C. Pickel, UC IPM Program, UC Cooperative Extension Sutter/Yuba counties
P. W. Weddle, Weddle, Hansen & Associates
P. Chevalier, United Ag Products, Ukiah
B. Knispel, Pest Control Adviser, Upper Lake
T. Lidyoff, Purity Products, Healdsburg
G. McCosker, AgroTech, Kelseyville
B. Oldham, Ag Unlimited, Ukiah
D. Smith, Western Farm Service, Walnut Grove
J. Sisevich, AgroTech, Kelseyville (retired)
B. Zoller, The Pear Doctor, Inc., Kelseyville

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