Apple-Grape mealybug

Phenacoccus maritimus

Pest description and crop damage The adult female is wingless and looks similar to a nymph. It can be up to 0.1875 (3/16) inch long. It has a well developed ring of waxy filaments around the sides of its body. The nymphs (or crawlers) are purplish and covered with a powdery wax coating. As they get older, the coating gets thicker, and a fringe of wax filaments develops. Mealybugs cause damage by secreting honeydew. Honeydew is cast off in small drops and falls down through the canopy. When it lands on fruit it causes a coarse, black russet, which is similar to pear psylla russeting. However, mealybug russeting is scattered over the fruit surface, while honeydew from psylla is in patches or streaks.

Biology and life history Grape mealybugs overwinter as crawlers in egg sacs beneath bark scales and in cracks. Crawlers start emerging from egg sacs at the beginning of bud swell and begin feeding on the bases of buds. When buds open they go directly to new shoots and leaves. Once settled, the crawlers start feeding and become progressively harder to kill. First generation nymphs mature during late June and July in the Northwest. Adult males appear first, mate with last instar nymphs or adult females and die. Receptive females release a pheromone to attract males. Mated females migrate to sheltered areas, lay eggs and die in the egg sac. A partial second generation matures in late August and September. Nymphs of this generation sometimes settle in or around the fruit calyx.

Management-biological control

Little research has been done to date on the effectiveness of natural enemies in keeping mealybug populations at levels below economic damage. Parasitic wasps, predatory bugs, predatory beetles, lacewings, and spiders can take a considerable toll of mealybugs that use few broad-spectrum chemicals. A ladybeetle, the "mealybug destroyer" (Cryptolaemus montrouzieri), is considered an effective predator of mealybugs worldwide. It is available from some insectaries.

Management-chemical control: HOME USE

Stages 5-6: Pink spray, spring and summer

  • acetamiprid
  • azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use.
  • pyrethrins-Some formulations are OMRI-listed for organic use.

Management-chemical control: COMMERCIAL USE

Stages 5-6: Pink spray

  • buprofezin (Centuar WDG Insect Growth Regulator) at 34.5 oz/a as a ground application using a minimum of 20 gallons of water per acre. Do not make more than one application or apply more than 34.5 oz/a per growing season PHI 14 days. [Group 16]
  • diazinon (Diazinon 50W) 2 to 4 lb/a in up to 100 gal of water per application. Do not apply more than 12 lb/a per growing season. Do not apply more than two applications per acre per year. The minimum treatment interval is 14 days. See label for use restrictions. PHI 21 days. [Group 1B]

Spring and summer

  • acetamiprid (Assail 70WP) at 1.7 to 3.4 oz/a in up to 100 gal water per application. Do not make more than 4 applications per year or exceed 13.5 oz/a per growing season. PHI 7 days.[Group 4A]
  • buprofezin (Centuar WDG Insect Growth Regulator) at 34.5 oz/a as a ground application using a minimum of 20 gallons of water per acre. Do not make more than one application or apply more than 34.5 oz/a per growing season. PHI 14 days. [Group 16]
  • carbaryl (Sevin 4F) at 2 to 3 quarts/a in up to 100 gal of water per application. Do not apply more than 15 quarts/a per growing season. PHI 3 days. [Group 1A]
  • Chromobacterium subtsugae (Grandevo) at 2 to 3 lb/a. Under heavy pest populations, apply a knockdown insecticide prior to or in a tank mix, use the higher label rates, shorten the spray interval, and/or increase the spray volume to improve coverage.
  • diazinon (Diazinon 50W) at 4 lb/a in up to 100 gal of water per application. Do not apply more than 12 lb/a per growing season. Do not apply more than two applications per acre per year. The minimum treatment interval is 14 days. See label for use restrictions. PHI 21 days. [Group 1B]