Updated Insecticide Recommendations for Spotted Lanternfly on Tree Fruit

Insecticide recommendations for spotted lanternfly in tree fruit, updated January 2019.
Updated Insecticide Recommendations for Spotted Lanternfly on Tree Fruit - Articles

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Spotted lanternfly (SLF) is an invasive and important pest for grapes and tree fruit in Southeastern PA. Evaluation of insecticides for managing this insect in the 2018 growing season are now complete. There is no current economic threshold for SLF damage. Both nymphs and adults of this pest have been reported feeding on grapes, while only adults have been reported feeding on apple and peach. The most damage has been reported on grapes. While adult SLF have been observed aggregating and feeding heavily on apples, economic damage has not been observed to date. Young trees may be at a greater risk, and these should be watched carefully for SLF feeding.For more information about the damage that SLF causes, see " Spotted Lanternfly on Grapes and Tree Fruit ."

Results from 2018 insecticide trial on SLF nymphs on potted peach trees

In July, we tested 20 different insecticides for their efficacy against SLF nymphs on peach trees. In this experiment, we sprayed peach trees (2-year-old in 5-gallon pots) using the maximum labeled rate of the insecticide for peach at a typical spray volume of 50 gallons/acre. Previous work has shown SLF nymphs and adults to be very susceptible to direct sprays, but the goal of this trial was to assess how long the sprays would last (residual activity) and how often sprays would need to be re-applied to protect the crop. Peach and grape growers typically apply on a 10-14 day schedule, so the goal was not to determine mortality by spraying the nymphs directly on the tree. Some products have long pre-harvest intervals that prevent late season spraying just before harvest, which is often when the adult SLF are most active. Some products also have long re-entry periods that restrict activities in the orchards and vineyard for periods of several hours to several days, depending on the product used and the rate of application.

Heather Leach and David Biddinger assessing spotted lanternfly mortality on peach trees. Photo: courtesy Heather Leach, Penn State

For this evaluation, we placed field collected 3rd instar nymphs on peach trees in net cages after the spray had dried (about 30 minutes). Mortality was assessed after 48 hours of exposure and all SLF were removed from the tree at that time. Nymphs barely alive, but clearly intoxicated (moribund) were recorded as well, but for the purposes of this analysis were considered dead. Contact insecticides such as pyrethroids, carbamates and organophosphates kill quickly by contact, but others such as neonicotinoids may kill more slowly by interfering with the insect nervous system or feeding.

Products that failed to give 50% mortality at this time were discontinued from this study. Some of these products are being evaluated for longer-term feeding trials, but they were removed from this study, so only 17 products are shown in the table. Using the same sprayed peach trees (application was made only once), we placed new nymphs (mostly 3rd instar nymphs) 7 days after the insecticide application and again assessed mortality after 48 hours of exposure. If products failed to give at least 50% control at this time they were considered to have failed and further evaluations were discontinued. Those products that were still performing well were assessed again with new (mostly 4th instar) nymphs 14 days after the spray application, again assessing mortality 48 hours later. All treatments except Brigade failed to give at least 50% mortality and the experiment was discontinued at that time. Rain-fastness was not evaluated in this study, but heavy rains did occur prior to the 14-day assessment and some products did not last as long as expected, which could be explained by the rain. The average percent mortality of each of these compounds compared to an untreated control are presented in Table 1 below. Compounds that do not appear in the 7-day and 14-day columns were not evaluated because of low mortality in the preceding assessment.

David Biddinger and field crew setting up the insecticide trial against spotted lanternfly nymphs. Photo: courtesy Heather Leach, Penn State

Results from 2018 insecticide trial on SLF adults on potted grapevines

In September, we tested 15 different insecticides for their efficacy against SLF adults on grapevines. In this experiment, we sprayed grape plants (1-year-old in 3-gallon pots, cv. ‘Riesling’) using the maximum labeled rate of the insecticide for peach at a typical spray volume of 50 gallons/acre. The same methods as described above were used for this evaluation, except that 5 adults were placed on each grape plant in net cages after the spray had dried (about 30 minutes). Mortality was assessed after 48 hours of exposure and all SLF were removed from the grape plant at that time. The average percent mortality of each of these compounds compared to an untreated control are presented in Table 1 below. Compounds that do not appear in the 7-day and 14-day columns were not evaluated because of low mortality in the preceding assessment.

Insecticide results for control of spotted lanternfly nymphs on peach and grape

Peach

Product nameActive ingredientRate/acre testedMean % mortality 0 days after sprayMean % mortality 7 days after sprayMean % mortality 14 days after spray
Brigade 10WSBbifenthrin16 oz100 a100 a78.8 a
Carbaryl 4Lcarabaryl3 qt100 a100 a10.0 c
Imidan 70WPphosmet3 lb100 a96.7 ab48.1 bc
Vydate 2Loxamyl8 pt100 a83.9 ab2.2 c
Danitol 2.4ECfenpropathrin21.33 fl oz100 a80.6 ab24.1 bc
Actara 25WDGthiamethoxam5.5 oz100 a70.2 ab17.0 bc
Scorpion 35SLdinotefuron7 fl oz100 a55.9 cd24.5 bc
Acephate 97WDGacephate1 lb100 a45.8 cd---
Mustang Maxx 0.8ECzeta-cypermethrin4 fl oz100 a29.4 cd---
Sivanto Prime 1.67SCflupyradiferone14 fl oz100 a23.3 cd--
Lannate 90SPmethomyl1 lb100 a8.2 d---
Avaunt 30DGindoxicarb6 oz98 a------
Closer 2SCsulfoxaflor5.75 fl oz90.7 a62.8 bc23.0 bc
Assail 30SGacetamiprid8 oz89.5 a8.6 cd---
Entrust 2SCspinosad2.5 fl oz57.9 b24.4 cd---
Movento 2SCspirotetramat + LI-700 (2.6 g/L)9 fl oz37.9 bc------
Water Control------0.0 d25.2 cd0.0 c

Grape

Product nameActive ingredientRate/acre testedMean % mortality 0 days after sprayMean % mortality 7 days after sprayMean % mortality 14 days after spray
Brigade 10WSBbifenthrin16 oz100 a100 a94.0 a
Actara 25WDGthiamethoxam3.5 oz100 a100 a60.0 ab
Scorpion 35SLdinotefuron5 fl oz100 a98.0 a30.0 b
Carbaryl 4Lcarabaryl2 qt98.0 ab96.0 a22.0 c
Admire Proimidacloprid1.4 oz79.5 ab48.3 b---
Mustang Maxx 0.8ECzeta-cypermethrin4 fl oz64.0 ab88.0 a11.0 b
Sivanto Prime 1.67SCflupyradiferone14 fl oz46.0 bcd-----
Assail 30SGacetamiprid5.2 oz38.0 cd------
Closer 2SCsulfoxaflor5.75 fl oz20.0 cde------
Avaunt 30DGindoxicarb6 oz20.0 cde------
Imidan 70WP, high ratephosmet2.125 lb20.0 cde------
VenerateBurkholderia spp. strain A3964 qt14.0 de------
Imidan 70WP, low ratephosmet1.33 lb6.0 e------
Entrust 2SCspinosad2.5 fl oz4.0 e------
Delegatespinetoram5 oz2.0 e------
Water Control------20.0 e11.3 b10.0 b

Percent mortality of spotted lanternfly nymphs and adults after 48 h exposure to foliage sprayed with different insecticides. Different letters following each percent mortality mean within a column indicate a significant difference at a 95% confidence limit. The letter “a” represents the compounds with the highest mortality level, while the subsequent letters (i.e. “e”) represent lower mortality levels and means followed by the same letter were not significantly different. The maximum registered peach rates are not necessarily the same rates as those registered for grape.

Of the insecticides tested on peach in the table above, 14 of the 16 chemicals had excellent knockdown activity. Seven days after the application, the insecticides that still had above 60% mortality were: Closer, Imidan, Actara, Danitol, Carbaryl, Brigade, and Vydate. Note: Control mortality on the 7-day assessment (24.7%) was higher than the 0-day and 14-day assessments possibly due to very high temperatures. Only two products had mortality greater than 40% at 14 days after the application: Imidan (48% mortality) and Brigade (79% mortality). The Avaunt 7-day mortality reading was mistakenly not taken at the same time as the other products, but all nymphs when evaluated several days late, were dead indicating this product will at least last for 7 days.

Of the insecticides tested for adults on grape in the table above, 5 of the 15 insecticides evaluated had excellent knockdown activity. Seven days after the application, the insecticides that still had above 60% mortality were: Brigade, Actara, Scorpion, Cabaryl, and Mustang Maxx. On both the 14 day and 21 day (not shown) assessment, both Brigade and Actara had at least 60% mortality, and all other products failed at that time. Note that Imidan did not perform well in the adult trial with the two rates tested. However, in the nymph trial at the labeled rate for peaches (3 lb/acre), it performed very well. Both the rate and the life stage could be responsible for this variation.

Please note that some of the chemicals evaluated in this peach trial not are currently labeled specifically for use on SLF. However, many of the insecticides used for other pests in grape, peach, and apple (such as brown marmorated stink bug, Japanese beetle, and grape berry moth) will provide some protection against SLF damage. The control timing of sprays for BMSB adult in apple coincide with the movement of SLF adults into the orchards and two products which have special emergency (section 18) registrations for BMSB in apple are very effective on SLF. Results from this and future trials in the next few weeks are being utilized by several pesticide companies to modify their insecticide labels to specifically include SLF on their labels. To-date, these are the current insecticides that have a registered 2(ee) label modification for spotted lanternfly in Pennsylvania on peach or apple are: Imidan 70WP, Mustang Maxx 0.8EC, Avaunt 30DG, Actara 25WDG (peach only), Brigade 10WSB, and Sevin XLR Plus. Another excellent website where pesticide label modifications can be found promptly is the CDMS website. Of the above listed products, all have been shown to be effective against SLF. In particular, Brigade, Scorpion, and Carbaryl performed the most consistently between life stages and had the longest residual activity against SLF.

The table below provides a list of insecticides registered for use against SLF in tree fruit and grapes. Selection of insecticides for SLF control should take into account the other pests present, harvest date, the re-entry date, and potential non-target impacts. Always follow the specific label restrictions for your crop and state. The level of control achieved will depend on the SLF population within your farm and in the surrounding landscape, the timeliness of the application, coverage, and the product effectiveness. Remember to rotate classes of insecticides to reduce likelihood of insecticide resistance.

Organic control of SLF

Entrust (spinosad) and Venerate XC (Burkholderia spp. strain) were the only OMRI-approved insecticides evaluated in these studies. Of these, Entrust performed the best. However, it had 58% mortality for nymphs immediately after the spray but gave no appreciable control 7 days after the application, and very low mortality on adults. Direct sprays to the nymphs or adults would most likely increased the efficacy of this product, but the lack of residual control by this product indicates timely applications at shorter intervals are necessary. A request for a 2(ee) label amendment for Entrust was denied until more data could be provided. There are no OMRI-approved products that are currently labeled for use against spotted lanternfly.

Ongoing studies

The data presented here are from trials done on SLF nymphs and adults on potted peach and grape at the Peiffer Turf Farm at the Penn State University Berks Campus. We are continuing to test effective insecticides against spotted lanternfly, including evaluating slower acting compounds against SLF that may give better long-term control or are safer to pollinators and biological control. We also plan to evaluate insecticides applied at different rates. Pyrethroids in particular are very disruptive to biological control , and may cause flares of secondary pests such as mites, aphids, scale, or mealybugs. Mites in particular have problems with late season pyrethroid applications made for BMSB and presumably will for SLF control since the timings are nearly identical. Trials at the Penn State University FREC has shown up to 80 times more overwintering European mite eggs after a single fall application of a pyrethroid timed for BMSB control just before harvest. Fruit growers with no history of mite problems have been overwhelmed when these eggs hatch early in the following spring and predatory mites have been wiped out from the pyrethroid spray or so reduced as to not keep up with the pests. Then eitherearly season foliar injury occurs and/or expensive miticides are needed. A similar situation can occur when the predators and parasitoids of Wooly Apple Aphid and San Jose scale are eliminated with a fall pyrethroid spray.

Previous trials on apple for BMSB control with fall applications of neonicotinoids did not cause secondary pest outbreaks and analysis of pollen and nectar samples taken the following spring did not have detectable residues of the insecticide. We will examine tree fruit and ornamental trees at bloom in 2019 to determine if SLF fall spray will carry over to the nectar and pollen the following spring where they may impact native pollinators and honey bees . It is not completely known what the effects of Imidan or Carbaryl applications made so late in the season would have on secondary pests, but recent trials have shown our predatory mite, T. pyri, is completely resistant to both insecticide classes. It is known that the increased level of egg laying in European red mites from pyrethroids is not associated with the organophosphate and carbamate insecticides, even in the days with they were more widely used. These SLF control trials have been made available to most pesticide companies so that they will be able to make label changes if necessary. Registrations and recommendations change, so keep informed through our website and your local extension educator.

Insecticides for control of spotted lanternfly in tree fruit

Please note that registrations and labels may change, and human error is always possible. You must check the most current label before applying any pesticide.