Across Napa Valley, hospitality teams have an important task - to answer questions and educate tasting room visitors about the vineyard! To help your teams respond confidently, the Napa Valley Grapegrowers hosts Seasonal Vineyard Walks for hospitality professionals, a complimentary educational experience on seasonal and sustainable vineyard practices.

July 19 at Paraduxx: Integrative Pest Management

Cultural Practices

Cover Crop
In order to enhance biological control its important to establish habitat for predator and parasitoids. Flowering plants provide nectar and pollen, which some adult predators like lacewings need to consume. Some common insectary plants include California Poppy, Lacy Leafed Phacelia, Carrot, Alyssum, and Clovers. Native vegetation between vine rows and avenues can also provide habitat for beneficial insects. No-till or alternate tillage systems are utilized to increase biodiversity and reduce dust in a vineyard.  

Common Pests in the Vineyard

Mealybugs

Mealybugs
Mealybugs are soft and oval, have a white waxy covering, and are roughly a ¼” long. Mealybugs appear on trunks and cordons in the spring. As temperatures warm in summer, they can be found on all parts of the vine including leaves and clusters. Ants and mealybugs are known to have a symbiotic relationship. Ants will protect and fend off predators, as mealybugs excrete honeydew.

Leafhoppers

Leafhoppers
Nymphs and adult leafhoppers feed on leaves removing the contents of leaf cells. When populations are high the entire leaf may become pale yellow or white. Leaf-drop may occur, resulting in delayed ripening and sunburn to fruit.  

Spider Mites
Spider mites damage grape leaves by puncturing cells and sucking out their contents. In heavy infestations damaged leaves will turn yellow or red (red varieties).

Beneficial Insects

Lacewing (Chrysoperla spp.)

Lacewing (Chrysoperla spp.) are generalist predators, meaning they target a broad spectrum of small insects and mites. In grapes,  lacewing can be used to combat mites, mealybugs, leafhoppers, whiteflies, and caterpillars. All lacewing larvae are predaceous, but adults of lacewings are not predaceous and feed on nectar and pollen. Larvae of the lacewing attack prey and suck their bodily fluids.

Anagyrus pseudococci

Anagyrus pseudococci is a parasitic wasp that attacks the third and fourth instar of vine mealybugs and can play a major role in controlling mealybug in grape. Effective ant control must be implemented to have successful establishment.

Mealybug destroyer Cryptolaemus montrouzieri can be used to control mealybug in grapes. Larvae mimic mealybugs in appearance and odor, which allow them to feast on their prey with little disturbance from protective ants. Females can lay up to 400 eggs in “Hot Spots.” Young larvae prefer eggs and early instar mealybugs, while older larvae and adults feed on all stages of the mealybug. They can consume 30 to 70 mealybugs per day.

Scouting

When scouting a ranch, it is important to look for both macro and micro issues. This means reporting a broken irrigation valve as well as tracking mite activity - you're essentially becoming the eyes and ears of the vineyard team. The reports of a scout directly impact the decision making of the viticulture and vineyard operations teams.

The following are general scouting instructions:
Overall Vineyard Observations: anything broken, missing signage, gate/fence problems, excessive vertebrate problems
 
Entomological

• Mites: Count population per leaf as well as frequency of mite appearance per 10-15 leaves. Start by looking in the basal area of canopy and then to mid then high canopy.
• Leafhoppers: Nymph counts (Frequency Vs Population) - damage is defined as stippling of leaves
• Thrips: in shoot tips (during active growth) and clusters during bloom - causes halo pattern scarring
• Beneficial presence: Yes/No    +    Low, Moderate, High

Note: Mite/ leafhopper foliage damage, as well as, how heavy damage and high/medium/low in canopy, as well as intensity throughout block or row
 
Weeds
Name/Species as well as frequency - high/medium/low. It is also helpful to have growth stage if possible. Since many people are moving away from systemic herbicides it has become more important to treat weeds when they're young or to mow/disc vineyard at an early stage of growth. Some weeds such as Queen Ann’s Lace can grow up into the fruit zone and can cause off flavors in wine.
 
Berry Appearance
Growth stage/ Sunburn/ thrip damage/ uneven ripening/ excessive tangling and bunching/ powdery mildew/ bunch stem necrosis or any unusual berry appearance
 
Virus/ Mold/ Rots/Mildew
These tend to be the most impactful things we scout for besides insect pests. Mildews and molds especially can spread very fast and once they have taken over they are hard to get rid of. Although mold, like botrytis, can be valued for the making of some wines, most molds/viruses and mildews can have adverse effects on wine quality.

• Where/ when/ how aggressive (aka frequency)/ dead or alive/ damage?
• Powdery Mildew/Downey Mildew: On leaves and/or fruit? How many clusters are infected?
• Botrytis/Green mold: How widespread? Appearance?
  
• Viruses: Pierce’s Disease/ Leafroll/ Red Blotch and more

Water/ Vine Stress
Shoot Tip termination stages:

• Stage 1: Long tendrils grown past shoot tip
• Stage 2: Tendrils equal to shoot tip
• Stage 3: Dead tendrils or no tendrils

Rate of shoot growth slows and the shoot tips gradually become more grayish green, like the mature leaves. Tendril drying and abscission is also a useful early indicator of vine water stress. As water stress continues, leaves appear wilted, particularly during midday heat. Under prolonged and severe stress, leaves curl, brown, and eventually drop.
 
Nutrient:
Diagnosing nutrient deficiencies or excess can be very difficult without a tissue analysis done in the lab. A vine can be deficient in more than one nutrient or can have a toxicity plus a deficiency. Usually taken during 50% bloom or sometimes at 50% veraison, most farming companies take leaf blade or petiole analysis at least one to two times a growing season. The results help growers indicate which foliar nutrients or injected nutrients to apply. Lacking in nutrients can significantly and negatively affect fruit or canopy during the most key time of the year...harvest.

​When a scout reports they look in the canopy high/mid/low as well as reporting on frequency or if it is just single vine or pattern… basal or meristem (bottom of canopy or shoot tip) – pictures are good for reporting because it is important to stay as objective as possible.

​Harvest and winterization

***More information coming soon***

Past Seasonal Vineyard Walks