Distinguishing Brown Marmorated Stink Bug Injury in Stone Fruit

-Dave Schmitt, Program Associate Rutgers Fruit IPM

Typical cat-facing injury on stone fruit always starts with a small puncture, followed by bleeding from the wound. At this time of the year there are several conditions that can cause similar symptoms. Because controlling Brown Marmorated Stinkbug (BMSB) requires a radical departure from traditional IPM programs, its important make sure that the injury is identified correctly before applying a remedy. The following picture essay should help to make the distinctions between

• BMSB Injury 
• Tarnished Plant Bug Injury
• Bacterial Spot

Brown Marmorated Stinkbug Injury 

BMSB injury starts with similar symptoms to native cat-facing insects, namely a small puncture that bleeds sap from the skin. Later the injury becomes a distinctive sunken spot as opposed to the scarring and malformation that characterizes native plant bug feeding (figure 1 as opposed to figure 2).

Fig. 1: BMSB Injury just prior to pit hardening. Note the bleeding and sunken spots.

Fig. 2: Native stink bug plant injury just prior to pit hardening. Note the shallow scarring.

If the BMSB injured area is cut one can see a brown mass of dead cells, not unlike cork spot of apple, that extends deep into the flesh (figure 3).

Fig. 3: BMSB Damage. Note the deep corky areas beneath the injury.

Physiological Injury 

Various physiological conditions can lead to bleeding that can be mistaken for insect injury. The distinction can be made by cutting into the fruit to determine whether or not the bleeding emanates from the pit or runs along beneath the surface (figure 4). Physiological injury will not be associated with any pattern of mouthpart entry. It will “wander” in an internal often random pattern, not be associated with corky tissue, and will usually start at an injured pit.

Fig. 4: Physiological injury with bleeding throughout peach flesh an emanating from the pit. Note the distinctive slits in the skin.

Tarnished Plant Bug (TPB) Injury 

TPB injury is often less malforming than native stinkbug injury, especially if it occurs late in the spring or during the summer. Characteristic bleeding is present at first with later more inconspicuous scarring (figure 5).

Fig. 5: TPB Injury just prior to pit hardening. Note the bleeding and superficial scarring.

Bacterial Spot 

Bacterial Spot symptoms also often start with bleeding. Water soaked areas can be seen about 3 weeks after infection that eventually darken causing deep pitting of the skin and flesh (figure 6).

Fig. 6: Bacterial spot symptoms on Peach just prior to pit hardening. Note the faint water soaked areas in the upper right and bleeding on the lower left.

Proper identification of injury is essential to choose a set of effective control measures, and can help to avoid costly and unnecessarily harsh tactics. If you are unsure of the cause of damage, extension personnel will happily try to identify it. Don’t hesitate to contact us!