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Management Options For The Stink Bug Complex On Pome Fruit Near Harvest. August 24th, 2020

Green Stink Bug on Pink lady

The brown marmorated stink bug (BMSB), Halyomorpha halys (Stål), is an Asian invasive arboreal pest in urban and agricultural environments, residing and feeding on a broad range of host plants. Significant and economic injury to tree fruit and vegetable crops has been well documented since 2011. Overwintering populations of the insect reside in man-made structures, causing home pestilence, provides the insect with this biological advantage in the cold climates of the northeast. The green stink bug, Chinavia halaris (Say), is also highly polyphagous arboreal insect having many host plants, and is a common pest of seeds, nuts and fruit in both the nymph and adult stages across the northeastern states. Both of these insects are a late season threat to pome fruit.

Action Threshold: The populations of brown marmorated stink bug have been steadily on the rise this season (Graph 1). Heat and drought conditions during the past three months have provided idyllic conditions for survival and reproduction. Very high nymph numbers have been recorded throughout much of the region and are now transitioning to adults in the southern Hudson Valley. BMSB adults have exceeded the 10 adult per week per trap threshold in many Hudson Valley sites. Both green and brown marmorated stink bug were also found feeding in pears and peaches this week, requiring management in orchards where BMSB are observed on fruit.

Simply looking forward, weather conditions over the next ten days are conducive for BMSB population increases that may give rise to movement into orchards followed by fruit feeding and economic injury as the week progresses. Traps with duel lures to attract green and brown marmorated stink bug placed along the wooded edge perimeter of tree fruit orchards should be monitored closely for increasing movement of the pests into orchards.

In Highland, NY we observed our first BMSB 2nd instar nymph on the 17th of May, suggesting eggs were laid during late April or early May given our cool spring temperatures. As day-length drives stink bug reproduction, 13.5-hours of daylight are required for the onset of BMSB mating and egg-laying to begin a second generation. In Geneva, NY, overwintering adults initiate the reproduction cycle from April 29th through Aug 13th while the Hudson Valley Research Laboratory in Highland, NY would begin on May 1st on through Aug. 11th.

Stink Bug Injury To Red Delicious

The temperature requirements to complete the 1st generation of BMSB is 1224 DD50. NEWA station temperature degree-day accumulations during 13.5-hours of daylight suggests a second generation of egg production began on the 12th July in Highland and 15th July in Geneva this year. This timing of oviposition and 2nd generation hatch giving rise to the nymphs and developing adults we have been observing.

Pest management challenges: As we approach harvest, populations of adults will increase while the volume of fruit on the remaining trees will decrease, intensifying damage feeding by stink bug to these late varieties remaining on the tree. In years past we have seen varieties harvesting in mid-September begin to express high levels of fruit injury in high pressure blocks. This implies that management to these varieties should begin from mid-late August and up to harvest. Most pronounced injury in the Hudson Valley has been observed on late peaches, Bartlett and Bosc pear, Red Delicious, Empire, Golden Delicious, Ruby Frost, Fuji and Pink Lady apple.

Adult BMSB On Apple.

BMSB simply does not fit traditional IPM models for management. Damage appears 7-14 days after fruit feeding requiring prophylactic management based on trap and scouting observations. The insect aggregates in late season flight to crops, migrating to and from woodlands to tree fruit. The insect has a large body mass and even when feeding, has minimal exposure to the insecticide requiring high insecticide rates for residual contact. Pre-overwintering feeding activity of BMSB in the orchard requires late season insecticide residue. Yet late season applications may exceed MRL’s, especially under drought conditions if rains that are needed to wash off residue are belated.

Stink Bug Management: The majority of insecticides when applied directly or as residual produce mortality to the target pest. As we approach harvest, essential considerations for insecticide decision-making using these materials should include insecticidal efficacy, effective use rate, residual activity and pre-harvest intervals.

The link to a list of BMSB management insecticide decision making providing an ‘Efficacy Comparison of BMSB Insecticide Tools for Orchard Tree Fruit Management’ for pyrethroids, neonicotinoids and pre-mixed tools can be found here. Last weeks Scaffolds (Pg. 4) also provide the links to Section 18 labels for the three labels for Bifenthrin, which need to be on hand during applications.

A Novel Mode of Action – Venerate XC: Keeping BMSB from feeding on the fruit is at the crux of our stink bug management program as we near harvest. Killing the insect as it moves into the orchard and onto the fruit is the traditional method of crop protection and proven to be very effective. Yet limitations, based on the material pre-harvest intervals constrain their use near harvest. There are no effective pyrethroids, neonicotinoids or pre-mixed insecticide tools that permit their use within the 7-day to harvest window with very few options available during the days prior to fruit harvest.

The development of newer classes of insecticides that produce an anti-feeding response in the pest provides an additional mode of action for BMSB management. Both Corteva insecticide Closer 240 SC (classified as a Group 4C insecticide / neonicotinoid – 7 DTH) and Venerate XC (microbial-based insecticide with multiple modes of action and 0 DTH) have anti-feeding activity against BMSB. The 0 DTH of Venerate provides BMSB management up to the day of harvest under high risk conditions.

During recent studies employing the bio-insecticide Venerate XC to reduce BMSB feeding to fruit we found some encouraging results. In one investigation four insecticides, Closer 240 SC, Venerate XC, Bifenthrin EC and Actara 25 WG were tested at the highest labeled rates employing topical applications made to the insect. These adults were either rated for mortality (Table 1) or placed on untreated apple and confined to feed on the fruit (Table 2). A complimentary study using untreated insects placed on treated fruit with insecticide residue was also conducted (Table 3). The insects were removed after 7 days to determine mortality and within the confined arena, fruit was examined to determine aspects of feeding injury. This trial demonstrated the efficacy of Venerate XC to inhibit BMSB feeding, comparable to both conventional and novel insecticides. Venerate showed no mortality of the pest but was comparable in fruit feeding reductions in this study.

The complete study can be found in our 2017 report, ‘RESULTS OF 2017 INSECTICIDE AND ACARICIDE STUDIES IN EASTERN NEW YORK’ pages 23-28. and as a PowerPoint presentation.

Venerate XC label requires a 4 hr. REI and has a 0 day PHI. In mixed blocks often requiring multiple picks, the use of Venerate XC has been shown to effectively reduce BMSB feeding injury to fruit 7 days prior to harvest. Although this insecticide provides no toxicity to the insect, it effectively reduced feeding over 7 days. A Technical Information Bulletin is available for the use of Venerate XC bio-insecticide brown marmorated stink bug on apple.

Table 1. Efficacy (mortality) of insecticides applied using 2 uL to the BMSB adult thorax using the highest labeled rate for each product tested.

Table 2. Results of topically treated and caged adult BMSB on untreated Red Delicious to inhibit fruit feeding over a 7-day interval.

Table 3. Efficacy of insecticide residual on Red Delicious to inhibit BMSB adult fruit feeding, placed 72 hours post application and over a 7-day interval.