University:
University of Georgia
Course:
BIOL-4241 | Entomology
Academic year:

2024
Views:

390

Pages:

33
Author:

Tyshawn Shaffer

Monitoring Common Insect Pests in GA Vineyards Outline • Common grape insect pests – Monitoring and biology of pests – Timing of insect activity in the field Outline • Common grape insect pests – Basic biology – Timing in field Common Grape Pests 1. Grape flea beetle 2. Grape phylloxera 3. Grape mealybugs 4. Thrips 5. Leafhoppers / sharpshooters (for Pierce’s disease) 6. Grape berry moth 7. Mites 8. Japanese beetles 9. Grape root borer 1 3 2 5 4 6 7 8 10. Spotted wing drosophila 9 10 Monitoring and biology of pests Grape flea beetle • Metallic blue-green beetle, ~1/5 in long – Adults feed on the unfolding leaves – Eat holes into the sides of buds and gouge out the contents as the buds swell • Larvae are brown with black spots, 3/8 in • Larvae feed on grape leaves for 3-4 weeks • Monitor: – Active early in the spring on warm, sunny days – Shiny beetles easily spotted on buds and canes – Survey 25 vines at each of the five locations – Bud damage 4% or more à management needed Grape phylloxera • Native to eastern US • Tiny, pale yellow sap-sucking insects • Feed on the leaves and roots – Create galls on leaves and roots – Stunting and/or death of European varieties • The mobile crawler stage of phylloxera is susceptible to insecticide treatment • Resistant American root stocks are key Grape mealybugs • Flat, white, and oval shaped – Filaments along the perimeter of the body – Two especially long protruding from rear • Become active in spring – Multiple generations a year – Populations are highest on vigorous vines – Generally more severe on late-ripening varieties • Mealybugs can vector grapevine leafroll virus • Honeydew supports the growth of sooty mold • Monitoring: – Check under bark on spurs or loose bark of prunings – Sooty mold and/or ants indicate mealybugs – Pheromone traps can monitor adult males Thrips • Small, 0.04 inch long, with distinctive feathery wings • Western flower thrips and grape thrips are the most important species – Western flower thrips populations peak in spring • Coinciding with grape bloom – Grape thrips populations peak in early summer • Coincides with peak vine growth • As growth slows, the numbers of thrips decreases • Damage includes: – Stunted shoots and leaf stippling/necrosis – Halo-spotting on the fruit when they oviposit in berries – Scarring of berries with their feeding • Generally not a problem in wine grapes Leafhoppers / sharpshooters (for Pierce’s disease) Glassy-winged sharpshooter • Small insects with piercing-sucking mouthparts – Feed upon xylem or phloem tissue – Often cryptic in coloration – hard to visually monitor Blue sharpshooter – Adults are expert jumpers and are strong flyers • Potential to vector Pierce's disease of grapevines – Several culprits, including glassy-winged sharpshooter, blue sharpshooter, and versute sharpshooter – The causal agent is the bacterium Xylella fastidiosa • Monitoring: – Begin at bud break – Use double-sided yellow sticky traps – Hang traps every 150 feet at canopy height – Check traps weekly Versute sharpshooter Sharpshooter/leafhopper community 2% 0% 0% 2% Versute sharpshooter 0% 0% Red-banded leafhopper 10% Broad-headed sharpshooter Constricted leafhopper Yellowheaded leafhopper Lateral-lined sharpshooter 86% Speckled sharpshooter Glassy-Winged Sharpshooters Sample date 29-Jul 22-Jul 15-Jul 8-Jul 1-Jul 24-Jun 17-Jun 10-Jun 3-Jun 27-May 20-May 13-May 6-May 29-Apr 22-Apr 15-Apr 8-Apr 1-Apr AVerage sharpshooters per trap Sharpshooter/leafhopper activity 180 160 140 120 100 80 60 40 20 0 Grape berry moth • Adult moths, different shades of brown with grey saddle – Eggs laid on grape stems, blossom clusters, or berries – Larvae are cream, then gray-green, then purple when mature, 3/8 in long – Overwinter as pupae in silken cocoons in fallen leaves • Economic damage is primarily to the berries – Larvae enter berries, creating tunnels (dark surface) – Create webbed clusters • Monitoring – Pheromone available for monitoring – A prebloom generation may exist in some regions – 2nd generation near bloom time, with 3 or 4 gens – 50% emergence at 187, 869, and 1094 DD after first male catch Date 27-Sep 20-Sep 13-Sep 6-Sep 30-Aug 23-Aug 16-Aug 9-Aug 2-Aug 26-Jul 19-Jul 12-Jul 5-Jul 28-Jun 21-Jun 14-Jun 7-Jun 31-May 24-May 17-May 10-May Moths per trap GBM activity 20 18 16 14 12 10 8 6 4 2 0 Mites • European red mite (ERM), Panonychus ulmi, • Two-spotted spider mite (TSM), Tetranychus urticae, • Can be a major pest within vineyards – Leaves have mild chlorotic spots and become bronzed if populations are sufficiently high – Severe infestations may result in defoliation – No direct fruit injury à reduction in photosynthesis negatively affects fruit quality – May lead to reduced shoot growth and fruit bud in the following year Mites Two-spotted Spider Mite Leaf damage European Red Mite Adult Female Webbing Male Monitoring for Mites • During the dormant period: – Inspect vines for overwintering ERM eggs – Clusters of of tiny (less than 1/50 inch), red spheres • Post-bloom: – Assess leaves for adult ERM and TSM mites – Use hand lens to inspect leaves – Tap branch and collect mites onto white sheet of paper • Chemical control should be considered only if ERM exceed 10 ERM and/or 5 TSM per leaf Japanese beetles • Adults are shiny green with copper-colored elytra – Overwinter as white, C-shaped grubs • Can be severe pest of grape during the summer – Skeletonize leaves, rarely feeding on berries – Gregarious; present in great numbers on a few vines – Feeding concentrated in the upper part of the canopy – Feeding after veraison may impact fruit quality • Monitoring: – No specific threshold • Manage at about 15% of the leaves damaged • Or damage is found below top trellis wire Grape root borer • Adult moths resemble wasps • Each female lays an average of 300 eggs – Only 1.5-2.7% survive – Larvae drop to the ground and tunnel into roots – The life cycle takes two years to complete – Full-grown larvae are about 1 in long, white, and have brown heads – Adults emerge from soil in early summer • Damage reduces the productivity of the vine – Roots may be hollowed – A lack of plant vigor is usually the first sign – Vines eventually die Grape root borer monitoring • Bucket trap and pheromone – 1 trap per 2 acres – Begin mid-June – Check traps weekly • Check for pupal casings at vine base -J u n 6Ju l 13 -J ul 20 -J ul 27 -J ul 3Au g 10 -A ug 17 -A ug 24 -A ug 31 -A ug 7Se p 14 -S ep 21 -S ep 29 Avg. GRB per trap GRB activity Standard Mating disruption 30 25 20 15 10 5 0 Sampling date Spotted Wing Drosophila • Vinegar (fruit) fly • Adults are 0.07-0.13 in long, have red eyes - Males have a characteristic black spot on the tip of each wing - Females have a saw-like, ovipositor • Hosts include blackberries, blueberries, cherries, peaches, pears, plums, strawberries, raspberries, and grapes • Lay eggs in ripening fruit – Can transmit sour rot – Larvae feed and pupate within fruit – Full life cycle as quick as 9 days • Larvae may infest fruit at harvest • Monitoring and management are crucial Male Female Monitoring for SWD • SWD is attracted to many volatiles – Including vinegar, wine, yeast, and fruit • Bait for traps – 1 tbsp dry yeast, 4 tbsp white sugar, and 2 cups of water + unscented dish soap – Solution should be 1–2 inches in trap – Traps can be made from plastic containers with 6 to 12, 3/16-inch-diameter holes about 2/3 around • Commercial lures and traps are available • Deploy traps 2 weeks before fruit begins to color • Place traps on the north side of rows at fruit level Checking Fruit for Larvae • Larvae may be present in fruit before adults are caught in traps – Also indicates whether sprays are effective • Collect intact, ripening grapes – Place fruit in a flat, dark pan or zip-lock bag – Add a salt solution (1⁄4 cup salt to 4 cups water) – Wait ~15 minutes for larvae to exit the fruit – Larvae found in recently ripened fruit are likely to be SWD Timing of insect activity in the field Bud swell through budbreak • Grape flea beetle • Mealybugs • Leafhoppers/sharpshooters (for Pierce’s disease suppression) Prebloom • Grape flea beetle • Leafhopper/ sharpshooters • Grape berry moth Bloom • Thrips Fruit set • Leafhopper/ sharpshooters • Grape berry moth • Grape phylloxera • Mites Cover sprays Peppercorn to veraison • Leafhopper/ sharpshooters • Grape berry moth • Grape phylloxera • Mites • Japanese beetles Mid-May to Early-June • Grape root borer (mating disruption) Veraison – 15o brix • Spotted wing drosophila Plus: • Leafhopper/ sharpshooters • Grape berry moth • Mites • Japanese and June beetles Female Pre-harvest – at least 35 days • Grape root borer Plus: • Leafhopper/ sharpshooters • Grape berry moth • Mites • Japanese beetles

Monitoring Common Insect Pests in GA Vineyards

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