SLF: Current Management Recommendations in Vineyards

By Katarzyna Madalinska, Megan Muehlbauer, George Hamilton, and Anne L. Nielsen

Spotted lantern flies on a tree

Spotted lanternfly adults congregating on tree of heaven

Spotted lanternfly was first found in northern NJ in 2018. Since then, populations are rapidly increasing and will substantially surpass those seen in 2019. Management of this pest is critical as we are still in the exponential growth phase of the population. There has been a 1300% increase in nymphs reported this year, which will most likely reflect higher numbers of adult SLF from previous years. This means that pressure from SLF adults will be felt more intensely by more vineyards this year.

The predominant life stage of the spotted lanternfly (SLF) seen across New Jersey during this time of year is the adult stage. That does not mean you will not see juveniles as well, which can appear black with white spots or their last juvenile stage which are red with black and white spots. The adult stage will be present until first frost.

Our current understanding of SLF adult behavior may aid in targeting management in vineyards. Right now, adult SLF are congregating in large numbers on hardwood trees along hedgerows or in bordering woods. It can be useful to identify one or a few spots around your vineyard where large numbers of SLF are feeding. One option for action at this time could be to target these trees with a backpack sprayer

using an insecticide labeled for SLF control as well as labeled for the tree species being treated. This is expected to decrease populations in general before they start reproducing but MAY not result in a decrease of pressure within the vineyard. While adults may be observed in the vineyard, right now SLF movement into the vineyard is minimal and is expected to dramatically increase in September and October. During the period of predicted peak SLF feeding within vineyards (September and October), the vines are storing carbohydrates for winter and excessive feeding by SLF can decrease winter hardiness by 1.5oC.

Movement into the vineyard will occur across several weeks and a strong edge effect will occur. However, SLF do not discriminate between vines that have been harvested or not. The treatment threshold used in South Korea is 10 SLF per vine, however, a more conservative threshold may be warranted to reduce populations and injury to the vines. If you can identify the more vulnerable parts of your vineyard you can target your insecticide application in those areas. The key is the application of an insecticide with long residual activity. There are several effective options for insecticide application (see Table 1).

Insecticides and their application rates are broken down in the table below. Be mindful of allowable uses and PHI when choosing an insecticide. After harvest there is more flexibility in insecticides available for application. We recommend the use of insecticides with a longer residual activity such as Bridgade post-harvest.

Table 1. Effectiveness of Insecticides Against Spotted Lanternfly Adults. SLF activity derived from PSU extension and Leach et al. Crop Protection 2019 v. 24 DOI:10.1016/j.cropro.2019.05.027

Trade name Rate per acre Total Use Systemic, Contact, Ingestion PHI (days) REI (hrs) Days of activity Labeled for SLF? SLF activity
Malathion 8F 1.88 pt 1.88 pt C, I 3 36 3-7 Yes, 2(ee) Excellent
Baythroid XL 2.4-3.2 oz 12.8 C, I 3 12 No Good
Scorpion 35SL 5 fl oz (foliar) 20.9 oz S, C, I 1 12 <14 Yes, 2(ee) Exc.
Brigade 10WSB 8-16 oz. 16 oz C, I 30 12 21 Yes, 2(ee) Exc.
Mustang Maxx 0.8EC 4 fl. oz. 24 oz C, I 1 12 <7 Yes, 2(ee) Good
Actara 25WDG 3.5 oz 7 oz. S, C, I 5 12 <21 Yes, 2(ee) Exc.
Assail 30SG 5.2 oz 2/yr S, C, I 3 48 0 Yes, 2(ee) on nymphs only Good
Carbaryl 4L 2 qt 10 qt C, I 7 12 <14 No Exc.
Avaunt 30DG 6 oz 2/yr C, I 7 12 0 Yes, 2(ee) Fair
Admire Pro 1.4 fl oz 2.8 oz C, I 0 12 <7 No Good
Belay 4-6 oz (foliar) 1/yr S, C, I 0/30 12 No Good/Excellent
Prepared by PennState  with modifications by Anne Nielsen

 

There are several reasons to manage adult SLF in September and October during peak movement.

  1. Adults feed on the canes, cordon, and trunk of grape vines. Excessive feeding has been shown to lower winter hardiness by >1.5°C.
  2. SLF females lay egg masses in October. Killing females prior to egg laying will decrease population growth the following year.

In October, female SLF prefer to lay egg masses on a relatively smooth surface that is positioned horizontally.  Within a vineyard, egg masses may be laid on posts, farm equipment, and the grape vines themselves. When looking for egg masses on your vines, be sure to examine any layers of peeling bark on the trunk or canes. However, if many egg masses are present in your vineyard, there are substantially more in any bordering wooded areas. Currently, we feel that management against the nymphs in the spring is more effective than targeting egg masses with an insecticide.

 

Help, Spotted Lanternfly Nymphs are in my Vineyard!

Management of Spotted Lanternfly Nymphs in New Jersey Vineyards

Megan Muehlbauer and Anne L. Nielsen

Vineyards in Salem and Hunterdon Counties in New Jersey are beginning to report spotted lanternfly (SLF) nymph sightings (Figure 1). These small black nymphs have white dots on their abdomens and will hop if disturbed. Although it is concerning to find them in large numbers in vineyards, we are not recommending that grape growers spray insecticides at the nymph stage.

Vineyard

Spotted Lanternfly Nymphs

(Photo Credit: https://www.pottsmerc.com)

Why? Thus far, there has been no definitive research showing that young SLF nymphs cause damage to grapes.  If SLF is feeding on grapes during the 1st and 2nd instar (nymph) stages, they are likely feeding on the fleshly new growth, not on the canes or cordon as the adults do.

However, these nymphs are also likely representing a very low number of the total population of SLF in and around the vineyard they are being seen at, because research has also shown that nymphs feed on multiple host plants.  To further elucidate details of SLF life cycle, and feeding habits, we are surveying to determine which life stages are found in commercial vineyards throughout the growing season.

As you make a decision on whether to spray the nymphs in your vineyard, It is important to keep these two points in mind.

1) Do not overuse pyrethroids in a vineyard as they can flare mealybug populations which vector leaf roll virus.

2) Save highly effective insecticides with good residual (Brigade, Actara, Scorpion, Carbaryl, and Mustang Maxx) for use against the adults in late summer through harvest.

If you want a material to apply now while the nymphs are just becoming active in the vineyard, the biological pesticides, BoteGHA (1-2 qt/acre) or BotaniGard 22 WP (0.5- 2 lbs/acre), are effective against the nymphs and will minimally impact other pests. These products have Beauvaria bassiana, a beneficial fungus that attacks insects and has good efficacy against SLF nymphs and a 4 hour REI.  Keep in mind when using B. bassiana materials, they take a few days to kill SLF and the fungal growth will turn the nymphs into fuzzy white cotton balls (Fig 2). As a biological material they work best under humid conditions. Recommendations tank mix compatibility for BoteGHA can be found here

Bug under a microscope

There are two other pests in NJ vineyards, grape berry moth and Japanese beetles, that commonly require management in the early summer. While there is no action threshold for SLF nymphs in the vineyard, management can be combined with existing pest management programs. Grape berry moth timing is approaching and we recommend using an insecticide that is effective against both SLF nymphs and grape berry moth if you have SLF nymphs in your vineyard (Table 1).

Just remember that the degree-day timing for grape berry moth is based on using growth regulators or diamide chemistries and application of a broad-spectrum material would be applied 1-2 days after the predicted timing. Japanese beetles typically occur in late June/July and again, there are insecticide materials that are effective against both SLF nymphs and Japanese beetle (Table 1).

Table 1. Insecticide efficacy against SLF nymphs and key grape pests

Rating of Insecticide Efficacy*
Insecticide SLF Nymph ** Grape Berry Moth Japanese Beetle
Avaunt 30SG E G G
Brigade 10WSB E E
Entrust 2SC F G
Imidan 70WP E G
Carbaryl E G G
Actara 25 WG E G

 

*E – Excellent; G – Good; F – Fair; ‘-‘ not rated

**H Leach, DJ Biddinger, G Krawczyk, E Smyers, JM Urban 2019 “Evaluation of insecticides for control of the spotted lanternfly, Lycorma delicatula, (Hemiptera: Fulgoridae), a new pest of fruit in the Northeastern U.S.” Crop Protection 124:104833

 

The recommendations for spotted lanternfly control are centered around the adult stage which are considered the primary damaging stage.  If adults are found in your vineyard they likely warrant management. In 2019 we saw SLF move into Northern NJ vineyards in large numbers at the end of September. It is important to note that they do not discriminate between vines that have been harvested or not. The only available threshold for SLF in grapes is 10 adults/vine, however this is quickly exceeded in some vineyards. We are recommending that growers apply a border spray targeting the vines on the borders or the first few panels if rows are perpendicular around your vineyard, with a focus on areas near hedgerows as it has been shown that those are the areas that SLF if most likely to congregate in at higher densities.  Further information on adult SLF control, recommended insecticides and rates will be in a forthcoming Plant and Pest Advisory Post.

Spotted Lanternfly Updates

Spotted lanternfly (SLF) populations are very active in multiple NJ counties such as Hunterdon, where large numbers of adults can be seen feeding. As of last week, the majority of adults were observed feeding on tree of heaven. Where possible, tree of heaven should be treated with either an herbicide and/or an insecticide. PSU has information on treatment here https://extension.psu.edu/tree-of-heaven

Based on observations in Pennsylvania, feeding by adult Spotted Lanternfly in grapes can reduce overwintering survival and may have broader impacts to vine health. Spotted lanternfly is a phloem feeding insect that feeds directly on the cordon, not on the fruit. As they feed, they expel the extra sugars from their bodies in the form of honeydew. Honeydew can buildup underneath trees or on plant material beneath vines and can be colonized by sooty mold fungi. In grapes, sooty mold can develop on clusters, significantly reducing quality, although this has not yet been observed in the USA. More importantly in areas with high SLF populations, vine health has deteriorated quickly. In Pennsylvania both a decrease in winter hardiness and vine death has occurred.

Vines should be watched closely to determine if SLF adults are dispersing into the vineyards and feeding. Populations will likely be higher along vineyard edges. If feeding occurs, an insecticide treatment may be warranted. The adults have not started to lay eggs yet so this is a critical time for population management. Multiple insecticide materials are effective against the adult stages. Recommendations from PennState in grapes are:

Pennsylvania State University Insecticide Recommendations Against Spotted Lanternfly

 (*modified for space)

Trade Name Active Ingredient Class

(IRAC Group)

Rate per Acre PHI (days) REI (hours) Labeled for SLF on Grape in PA? Life Stage Tested Longevity SLF Activity
Brigade 10WSB bifenthrin Pyrethroid

(IRAC 3)

16 oz 30 12 Yes, 2(ee) Nymphs Adults **** ++++
Actara 25WDG * thiamethoxam Neonicitinoid (IRAC 4A) 3.5 oz 5 12 Yes, 2(ee) Nymphs Adults **** ++++
Scorpion 35SL * dinotefuran Neonicitinoid (IRAC 4A) 5 fl oz 1 12 Yes, 2(ee) Nymphs Adults *** ++++
Carbaryl 4L carbaryl Carbamate (IRAC 1A) 2 qt 7 12 No
Note: Sevin XLR has 2(ee)
Nymphs Adults *** ++++
Danitol 2.4EC fenpropathrin Pyrethroid

(IRAC 3)

21.33 fl oz 21 24 No Nymphs ** ++++
Malathion 8F malathion Organophosphate (IRAC 1B) 1.88 pts 3 12 Yes, 2(ee) Nymphs Adults ** ++++
Mustang Maxx 0.8EC zeta- cypermethrin Pyrethroid

(IRAC 3A)

4 fl oz 1 12 Yes, 2(ee) Nymphs Adults ** +++
Avaunt 30DG indoxacarb Oxadiazine (IRAC 22) 6 oz 7 12 Yes, 2(ee) Nymphs Adults * ++
Assail 30SG * acetamiprid Neonicitinoid (IRAC 4A) 5.2 oz 3 48 Yes, 2(ee) on nymphs only Nymphs Adults * +

Always follow the insecticide label for use and application instructions. Please note that there is variation in the residual activity of each material and some materials require a 2(ee) label for use in grapes. BotaniGard is also being evaluated as a biological insecticide by PSU.

New sightings of spotted lanternfly in NJ can be reported, along with a picture and address to slanternfly@njaes.rutgers.edu

Spotted Lanternfly Basics Webinars

In conjunction with the New York State IPM Program and the Department of Agriculture and Markets, the Northeastern IPM Center will host a collection of webinars, titled “Spotted Lanternfly Basics.” Each webinar will focus on, and be tailored to, a specific commodity group:

Spotted Lanternfly Basics for Grape and Apple Industries (Feb. 26, 2019, 1:00 p.m.). Registration link: https://cornell.zoom.us/webinar/register/WN_d_3KfxQ9SuKHyhk6pM7NCA

Spotted Lanternfly Basics for Hops, Berry, and Vegetable Growers (Feb. 26, 2019, 10:00 a.m.). Registration link: https://cornell.zoom.us/webinar/register/WN_ONViZLocSBCOKIv-sjoZVg

Spotted Lanternfly Basics for Christmas Tree Growers (Mar. 4, 2019, 10:00 a.m.). Registration link: https://cornell.zoom.us/webinar/register/WN_7eehVeBvSBOgM3aTXOtaew

Spotted Lanternfly Basics for Nursery, Greenhouse, and Landscape Industries (Mar. 4, 2019, 1:00 p.m.). Registration link: https://cornell.zoom.us/webinar/register/WN_u5mYQOHMSESWFcNoftt2Nw

All webinars will follow a similar format that covers spotted lanternfly biology, identification, and hosts, monitoring and management strategies, and a regulatory update. While the content may be relevant to audiences throughout the Northeast, management practices covered will be specific to New York. Participants will be encouraged to ask questions.

For more information and registration links, go to:

http://neipmc.org/go/mYey

Monitoring for SLF Egg Masses

Spotted lanternfly egg mass

Spotted lanternfly egg mass – photo by A.L. Nielsen

Spotted lanternfly is a new invasive species in NJ. Egg masses are brownish grey and generally laid on bark in early fall and appear like a smudge of mud. Adults are expected to start egg laying in August and continue through November or the first hard frost.

SLF eggs overwinter and can be laid on multiple hard surfaces, including fence posts, trees, patio furniture, fruit bins, landscaping stones, railway cars, etc. Due to this they can be easily transported and represent a significant risk to SLF populations spreading. Vehicles, stones, agricultural equipment, and fruit bins coming from PA or VA should be inspected for egg masses beginning in August. Within state movement is also of concern to prevent new populations. If found, egg masses can be scraped into a plastic bag and frozen to limit spread and future impact of this pest.