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Control of Pales and Pitch-Eating Weevils in the South
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Identifying Hazardous Sites


Weevil populations in the South tend to be high from year to year, and serious damage often occurs within a few days or weeks of planting, even in midwinter when the temperature moderates. Therefore, control decisions need to be made before planting. To make these decisions, the forest manager must be able to predict whether significant weevil-caused damage will occur on the site. The following sections provide guidelines for making that prediction for both species of weevils, and offer alternatives for controlling them. Most of the research on which these guidelines were based was done in areas where pales weevils were more common than pitch-eating weevils (i.e., eastern North Carolina, the Georgia Piedmont, southeastern Oklahoma, southwestern Arkansas). However, because of similarities in biology and behavior of the two species, and the good control obtained when using these guidelines in areas where both species occur,the guidelines apply to both species.

Hazard Rating

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In the past, attempts have been made to correlate the number of pales weevils trapped on a site prior to planting with the subsequent seedling damage, in an effort to develop a pales weevil hazard rating system for recently cutover pine land. Pales and pitch-eating weevils are easily trapped in nature, and under favorable conditions large numbers may be collected. Various resin-containing materials can be used for trapping. The most commonly used materials are pine bolts about 18 inches (0.5 in) long, split once, or discs freshly cut from living pine stems 5 to 7 inches (13 to 18 cm) in diameter. Discs should be I V2 to 2 inches (4 to 5 cm) thick (figure 6). These traps are placed on the ground in an infested area, with the cut surface flush on the ground. Weevils are attracted to this material by the odor of the resin. The weevils crawl under the traps at night where they may remain for many hours (usually until mid-morning), feeding and mating. Correlations have been poor, however, between the numbers of weevils found trapped on planting sites prior to planting and subsequent seedling damage.

Figure 6
Figure 6. - Split pine bolt and pine discs placed around loblolly pine stump to trap pales and pitch-eating weevil adults.

Until a reliable hazard rating system is developed which can predict weevil damage based on weevil population estimates, forest managers must depend on other circumstantial evidence to determine if control is necessary.

Nonhazardous Sites

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Weevil problems will not develop in certain planting situations, such as:

  1. Old fields and areas formerly covered with hardwoods, since weevils are not attracted to nonconiferous vegetation.

  2. Pine areas being regenerated by direct seeding, since weevils will have left the area before the seedlings are large enough to become suitable food.

  3. Pine areas cut and site-prepared before July, because weevils and their broods will either have died or migrated before the following planting season.


Hazardous Sites

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Weevil damage is likely to occur on pine lands harvested in July or later and replanted the following winter. Note, however, that in sites cut prior to July, a late summer or fall site preparation which knocks down residual pine stems will result in another influx of weevils, and seedling mortality should be expected. The size of the attracted population and the amount of damage apparently depends on the volume of pine cut during site preparation.

Damage may also occur in areas cut in the spring or even in I- to 3-year-old pine plantations adjacent to large freshly cut areas, but this damage is usually confined to 100-foot-wide border strips near the cutting. Seed tree cuts will also attract damaging populations of weevils. But by far, the most damage occurs in plantings on recently cutover or site-prepared pine lands.

Guide to Determining Weevil Damage Hazard

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A rule of thumb has been developed for the Piedmont and Coastal Plain regions of the South that can be used by the forest manager to determine weevil hazard: Pine lands cut and site prepared before July can generally be planted the following winter without control measures. However, on pine lands harvested in JuIy and later, or in older cuttings where residual pine is cut during late summer or fall site preparation, planting should either be delayed one year or seedlings should be treated with insecticide to prevent weevil-caused mortality.

This rule may not apply to pine sites in the southern Appalachians, where seedlings planted on sites cut before July would probably sustain damage.

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