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Pressure from Stink Bugs Continues in Apple Orchards

Posted: August 26, 2011

The brown marmorated stink bug (BMSB) continues to represent an unprecedented threat to our apple crop. The incessant feeding of growing nymphs and maturing adults poses a significant economic risk to maturing fruit as each probing or feeding by BMSB eventually results in a visible injury. A single BMSB adult or nymph in the orchard can potentially cause injury to many fruit. Another complicating element is the fact that fresh injuries from stink bug feeding are initially almost undetectable, but after only a few days, the injury can become very apparent. Since their actual feeding occurs under the skin of the fruit, it is only after the affected cells start drying that the symptoms of their feeding (i.e., corking) become visible (see picture). Also, since no fungal pathogens are transmitted during BMSB feeding, the affected area remains dry and no decay is observed. If BMSB feeding occurs just prior to harvest, it is quite possible that affected fruit will exhibit no visible signs of injury, but the characteristic depression on the fruit surface will develop after a period of time in storage.
Fresh injury on apple fruits caused by feeding of brown marmorated stink bug. Photo: Greg Krawczyk

Fresh injury on apple fruits caused by feeding of brown marmorated stink bug. Photo: Greg Krawczyk

Dr. Greg Krawczyk and Dr. Larry Hull, Penn State Fruit Research and Extension Center Entomologists

Based on our experiences from last season, we expect that stink bug feeding will continue at least until mid-October this year. BMSB adults will continue feeding as long as weather permits or until they begin moving towards their overwintering sites. This late season feeding can be very intensive, as adult stink bugs are trying to accumulate enough resources to survive the winter. While the BMSB adults are in their overwintering shelters, they do not feed so all resources need to be gathered before moving into their shelters.

Monitoring for the brown marmorated stink bug still remains an area that requires a lot of attention. While the currently used trapping systems started capturing both adults and nymphs over the past few weeks, there are still a lot of gaps in our understanding on how to interpret these findings.  The aggregation pheromone currently utilized in traps is not species-specific and it appears that it can attract higher numbers of individuals than the traps are capable of capturing.  But if detection of the stink bug is the goal of the monitoring activities, then those traps should be able to serve this purpose.

Fortunately, not every orchard will experience the same high pressure from the brown marmorated stink bug. Based on our current observations (through late August), the highest numbers of brown marmorated stink bugs were observed on the edges of orchards bordering with woods or various agronomic crops. We have seen hundreds if not thousands of BMSB in some soybean and corn fields, although not every soybean/corn field has high populations. But definitive, cautious scouting and monitoring of the vegetation surrounding an orchard should be very helpful in deciding if any special stink bug control treatment(s) is necessary. It is important to remember that the absence of stink bugs during the season, does not guarantee that they will not become abundant in the orchard just before harvest. BMSB is not an orchard resident pest and what management tactics were utilized to control BMSB during the season in any particular block cannot guarantee or prevent new individuals from infesting/re-infesting the site just prior to harvest.

In order to manage possible infestations, a careful monitoring program needs to be employed. If injured fruit or stink bugs are detected, then the decision will have to be made about the best approach to manage the problem. Insecticides still remain the most effective BMSB management tool, but none of them will protect fruit from some level of damage. Early detection of feeding BMSB will help to limit the damage but not eliminate it completely. The most effective products will control only the individuals present in the orchard at the time of the application (i.e., direct contact activity), but they will not stop newcomers from at least initially probing the fruit. Remember - each probing equals an injury.  Most of the effective insecticides provide only a few days of residual protection. The results of our currently conducted residual bioassays revealed that most of the recommended insecticides provide sufficient residual control of BMSB nymphs for at least 7 or even 12 days after the application (higher rates of product usually provide longer residual activity).   

The following list includes insecticides with significant activity against BMSB adults and nymphs, as well as the pre-harvest (PHI) information for each product. The BMSB adult efficacy rating is based on our earlier laboratory bioassay results conducted last winter and during this season.  

Acetamiprid (IRAC Group 4A) (Assail 30 SG)– 7 day PHI on pome and stone fruit; no more than 32.0 oz of formulated product per acre per season; BMSB adult direct contact mortality at 72 hours - about 87%.

Clothianidin (IRAC Group 4A)(Belay) – 7 days PHI on apples and pears; 21 days PHI on peach; no more than 0.2 lb AI per acre/per season is allowed; BMSB adult direct contact mortality at 72 hours - 100%.

Dinotefuran (IRAC Group 4A) (Scorpion, Venom, Special Section 18 emergency registration until Oct 15, 2011) – 3 days PHI on pome and stone fruit; no more than 2 applications of this active ingredient per season; BMSB adult direct contact mortality at 72 hours – about 98%.

Fenpropathrin (IRAC Group 3)(Danitol) – 14 day PHI on apples and pears; 3 days on stone fruit; no more than 0.8 pound of AI is allowed per acre/season; BMSB adult direct contact mortality at 72 hours – about 82%.

Imidacloprid (IRAC Group 4A) (Admire Pro, Leverage (imidacloprid mix with beta- cyfluthrin)) – Admire Pro has 7 day PHI on pome fruit; 0 days PHI on stone fruit; no more than 0.5 lb AI per season; Leverage SC 360 has 7 day PHI on pome and stone fruit; no more than 0.044 lb AI per acre of beta cyfluthrin and/or 0.088 lb AI per acre of imidacloprid. Admire Pro BMSB adult direct contact mortality at 72 hours – about 87%; while for Leverage the BMSB adult direct contact mortality at 72 hours – about 93%.

Lambda-cyhalothrin (IRAC Group3) (Warrior II with Zeon Technology, Taiga Z) – 21 day PHI on pome fruit; 14 day PHI on stone fruit; BMSB adult direct contact mortality at 72 hours – about 72%. 

Methomyl (IRAC Group 1A)(Lannate) – 14 day PHI on apples; 7 days on pears; 4 days on peaches; 1 day on nectarines (PA only).  On apples no more than 4.5 pounds of AI/acre is allowed; on peaches no more than 5.4 pounds of AI per acre/season; on pears no more than 1.8 pounds of AI per acre/season; BMSB adult direct contact mortality at 72 hours – about 90%.

Thiametoxam (IRAC Group 4A) (Actara, Endigo – (thiametoxam mix with lambda-cyhalothrin))- 35 day PHI for both products on pome fruit; 14 day PHI on stone fruit; no more than 0.2 lb AI lambda-cyhalothrin containing products or 0.172 lb AI (stone fruit) or 0.258 lb AI (pome fruit) of thiametoxm containing products per season. For Actara the BMSB adult direct contact mortality at 72 hours – about 95%; for Endigo the BMSB adult direct contact mortality at 72 hours - 100%. 

Always read the label before applying any pesticide

 

SEASONAL ACTIVITY OF FRUIT PESTS

2011 season - weekly captures of adult moths in pheromone traps located at Penn State FREC Biglerville, PA (Adams County): 

Species   7/07   7/14   7/21   7/28   8/04   8/11   8/18   8/25

RBLR        11        6        1      16      19      22      31      24           

STLM       65     161     137      52      27      39    123     159

OFM          6        3        2       2       32      22     27       30           

CM          15       43      26      20       25      45     20      19

TABM        1        3        4        4         4       2       2       2    

OBLR         0        1        1        2         1       3       0       0

Key to acronyms: RBLR - redbanded leafroller; STLM - spotted tentiform leafminer; OFM - Oriental fruit moth; CM – codling moth; TABM – tufted apple bud moth; OBLR – obliquebanded leafroller.

 

DEGREE-DAY TABLE: Accumulated degree-days base 43° F from Jan 01 for each reported year (courtesy of SkyBit, Inc.). The accumulated degree-days for the last date of the current year (Sep 01) mentioned in the table are based on the weather forecast. 

Site/Date               7/28    8/04    8/11    8/18    8/25    9/01

 

Biglerville, 2011       3029    3281    3512    3716    3919    4122

Biglerville, 2010       3145    3366    3612    3833    4043    4248

Biglerville, 2009       2637    2858    3078    3310    3541    3743

Biglerville, 2008       2727    2955    3150    3335    3529    3710

Biglerville, 2007       2732    2974    3218    3433    3603    3819

Biglerville, 2006       2771    3043    3260    3458    3676    3880

Biglerville, 2005       2676    2898    3130    3370    3571    3777

 

Rock Spring, 2011       2603    2833    3043    3227    3407    3577

Rock Spring, 2010       2742    2941    3156    3356    3542    3710

Rock Spring, 2009       2218    2411    2598    2814    3016    3184

Rock Spring, 2008       2324    2528    2696    2859    3034    3193

Rock Spring, 2007       2339    2596    2818    3011    3168    3360

Rock Spring, 2006       2391    2641    2837    3012    3203    3376

Rock Spring, 2005       2331    2551    2766    2986    3167    3347