Spotted Lanternfly (SLF) II - Scouting and Management
The Spotted Lanternfly (SLF) is now confirmed in Cecil and Harford Counties in Maryland, and has the potential to be a very significant pest in vineyards. For background information, please see the TimelyVit Spotted Lanternfly (SLF) I—Background, for basic information. This Timely Viticulture was created to give growers information on how to scout for the pest and some management options and strategies. This is a “newly introduced” which has already cause significant damage to Pennsylvania vineyards.
- For previously uninfected vineyards, a few adults may appear in early August, but typically the numbers are limited, do not cause significant damage, and therefore do not warrant a spray. High immigrating populations are not typically observed until late September into October.
- If you have not yet detected SLF in your vineyard, but know they are in the area, scouting for and monitoring Tree-of-Heaven (TOH) or other hosts (Sumac, Sycamore, Black walnut) adjacent to the vineyard is the best place to start.
- After SLF is established in the area, overwintering egg masses are commonly found on grapevine trunks and TOH but also on objects such as rock, vehicles, etc.
- When egg masses are located, destroy by scraping into a container with 70% alcohol and removing them from the vineyard.
- The emerging nymphs move from the surrounding woods and TOH to grape and other hosts. Young immature stages (1-3 instars) resemble a large black aphid with white spots (figure B); the final most mature immature stage (4th instar) develops bright red patches and are over 1/2” long (figure C).
- Nymphs and adults are vascular feeders (phloem and xylem) so they will primarily be found on trunks, cordons, and canes; they are NOT typically found on the foliage; all 4 immature stages of SLF can feed on grape wood.
- The majority of an SLF population within a vineyard is observed on the edge; on average, 54 percent of the SLF population is within the first 50 feet of the vineyard edge.
- In addition to the native population in the vineyards, large numbers of adults may migrate from surrounding areas in mid-August through the end of the season.
In mid-to-late summer and early in the fall the adults will heavily congregate on stems of Tree of Heaven and grapevines (figure G).
- Sooty mold patches on clusters and leaves can be a sign of feeding.
- In late fall, search and destroy efforts should switch to the location of egg masses. Adults lay egg masses on trees and nearby smooth surfaces, like stone, outdoor furniture, vehicles, and other structures. Again, destroy by scraping into a container with 70% alcohol and removing them from the vineyard.
- As with any insect pest, small populations are only causing minor damage and typically do not warrant control. Always remember if you apply an insecticide you may be disrupting the delicate balance with beneficial insects which may lead to other pest outbreaks (mites, aphids, etc.)
- After SLF is established in a vineyard (eggs laid the previous season), low populations of nymphs can be tolerated but should be monitored. For hot spots of dense populations of nymphs (i.e., >10–50 per vine), spot treatments may be needed.
- Nymphs have not been observed reinfesting vineyards like adults do, so typically only one application of insecticide is necessary (if at all). Short-acting insecticides are recommended.
- Applications targeted for grape berry moth and Japanese beetles in mid-summer will be effective in managing nymphs in the vineyard.
- Small populations of adults can be crushed or swatted by hand.
- There need to be multiple (5-10) adults per vine before you reach a threshold to manage.
- Penn State Extension has been testing insecticides for efficacy. There are a number of effective insecticides, with various REIs and PHIs. For a list of potential insecticides, please go to: https://extension.psu.edu/spotted-lanternfly-management-in-vineyards
- When populations are high in August, use residual activity and longer PHI now until you get close to harvest, then switch to the knockdown and shorter PHI materials during harvest. Utilize the long residual activity (and long PHI) materials after harvest for sustained control. As always follow the label and rotate chemical classes appropriately.
- Again, the majority of an SLF population within a vineyard is typically observed within the first 50 feet of the vineyard edge, so only spot treatments are typically needed.
- Currently, there are no known natural enemies of SLF that are thought to reduce populations in the United States. Some generalist predators (spiders, praying mantises, parasitoids, etc.) will attack and eat SLF. Two species of fungal pathogens have been identified attacking SLF in Pennsylvania.
- Neem oil and insecticidal soap can provide some control, but soaps do not appear to control adults.
- Application of insecticides may kill SLF within the vineyard, but be aware that reinfestation of SLF from the surrounding woodlot is possible.
Population Management Utilizing Tree Wraps/Banding
- The immature SLF does not fly, so they must walk up to their host (vines/tree).
- There has been some success (with trees) trapping the SLF on sticky bands placed around the circumference of the tree. Insects walk onto the band and are trapped.
- This can be effective in trapping and reducing the population, although we are not sure if it will work with grapevines with irregular flakey bark.