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Japanese Beetle Emergence: Stone Fruit, Apple & Grape Scouting and Management

We are now seeing the emergence of the Japanese Beetle with feeding on wild grape, especially to new succulent foliage. In newly planted trees and vines this reduction of leaf tissue may lead to reduced carbohydrate production and storage, resulting in decreased establishment and overwintering success.

Japanese beetle adult.

Japanese beetle adult.

We observed the first emergence of Japanese beetle, Popillia japonica, (2nd of July), a day later than last year. Emergence pressure usually builds over time. In the past few years we have seen high levels of emergence with significant damage to grape, newly planted and establishing tree fruit foliage, and in pick-your-own operations as a nuisance pest.

As the name suggests, the Japanese beetle is a non-native beetle, indigenous to Japan. The first sighting of this beetle occurring in the United States in 1916 from a nursery near Riverton, New Jersey. It is thought that beetle larvae migrated to the United States in a shipment of iris bulbs entering the country, prior to the onset of commodity port of entry inspections.

Japanese beetles have a univoltine life cycle (one generation per year). They overwinter as third instar larvae in the soil below the frost line. As soil temperatures warm in the spring, the larvae move closer to the soil surface. They complete pupation and emergence begins in late June in the Hudson Valley. Peak emergence generally occurs 4 to 5 weeks after initial emergence. At that time, emerging beetles crawl or fly in search of host plants to feed and mate. Japanese beetles are naturally gregarious and tend to aggregate on host plants once they establish.

The adult beetle is 0.6 inches long and 0.4 inches wide, with iridescent copper-colored elytra and green thorax and head. Females will mate shortly after they emerge from the soil only to burrow back into the sod to lay eggs, repeating this cycle through the early part of the summer. The larva or grub is cream colored and feed on roots of grasses for most of their immature life. The damage they inflict often causing high mortality to grasses in agricultural, lawn and golf course turf.

Japanese beetle are attractive to a ‘congregation pheromone’. This lure has been synthesized and is used in traps baited with both floral scent and pheromone. However, studies done at the University of Kentucky suggest that traps attract more beetles than they actually trap, thus causing more damage to surrounding crops than may have occurred were the trap not used.

Japanese Beetle Skeletonizing of Foliage

Japanese Beetle Skeletonizing of Foliage

The Japanese beetle is a serious pest of about 300 species of plants throughout the eastern US, and considered the most devastating pest of urban landscape plants in the eastern United States.

The beetle has been found to prefer feeding on apple, grape, stone fruit, soy bean, corn and diverse range of weed species. Apple, blueberry and raspberry are highly attractive to Japanese beetles and are more likely to have feeding injury compared to other crops in any given orchard. Japanese beetles have cultivar preference and are likely to select the most preferred of the cultivars available in each infested orchard.

Damage to plants by adult feeding results in the skeletonizing of the leaf, consuming foliage between the leaf veins.

It will also feed on ripening or damaged fruit, especially to early peach and apple varieties as ripening occurs shortly after Japanese beetle emergence. Managing the beetle on ripening fruit is often difficult due to pre-harvest interval limitations of effective materials.

Japanese Beetle Life Cycle

Japanese Beetle Life Cycle

Conventional Management Options:
Asana, Brigade, Baythroid, Danitol, Mustang Max, Warrior and pre-mix pyrethroid formulations provide a strong knockdown and mortality of adult beetles with residual activity lasting 7 to 10 days. Japanese beetles may also be repelled from fields with pyrethroid applications, reducing infestations of crops. PHI’s for pyrethroid insecticides vary with different formulations and various crops requiring close review of the label before use.

Carbaryl or Sevin is formulated as a liquid XLR Plus, 4F or 80S powder. Carbaryl is highly effective in codling moth, adult and nymph leafhopper and Japanese beetle control during the summer.

The Neonicotinoids: Provado, Actara, Assail can be used against the insect in tree fruit crops. This class provides two to five days of lethal contact activity before being absorbed into the foliage. They are locally-systemic, rainfast and do provide a level of repellency and knockdown with less direct mortality. Japanese beetles respond to insecticide rate and you should consider using higher labeled rates to achieve residual control of this insect.

Assail 30SG (EPA Reg. No. 8033-36-4581) is registered for use in pome fruit and grapes in NY. Along with control of CM, OFM, apple maggot, aphids, and leafhoppers, it has been noted that Assail applied at early infestation of Japanese beetle causes the beetles to stop feeding and eventually kills the adults. Assail recently received a federal label for use in stone fruits, not yet approved in NY for stone fruit.

Actara* labeled for use against JB under a Section 2(ee) for supression of JB on apple only. Under a Section 2(ee). The user must refer to the federally approved Actara label and read and follow all directions for use, restrictions, and precautions. It is a violation of federal law to use this product in a manner inconsistent with its labeling.The user should have this recommendation in their possession at the time of use. (http://128.253.223.36/ppds/525546.pdf)

Insecticide controls

Pre-mixed insecticides often contain lower rates of the two active ingredients then each can be applied individually in a tank mix. A single active ingredient may suffice in the case of Japanese beetle management. This is especially true if the limit labeled usage for an active ingredient reduces its use later in the season for insects such as Brown Marmorated Stink Bug (Actara / Thiamethoxam is one example). It is important to maintain active ingredient usage records regarding labeled restrictions of applications and per acre rates for each active ingredient esepcially regarding pre-mixes usage. Avaunt is also labeled for use in grapes for Japanese beetle, and will manage grape berry moth larva at this time.

Leverage 2.7SE should be reserved for those situations when the pest complex to be treated is appropriately matched to the combination of active ingredients and modes of action contained in the product. Not labeled for JB on apple.

Organic controls
The use of OMRI approved selective insecticides with zero day PHI’s can repel beetles and help achieve beetle-free fruit during harvest. A viable option for managing Japanese beetle is SURROUND WP, a white kaolin clay formulation applied to coat the surface of foliage and fruit to provide a barrier film for protection against insects. When applied in multiple applications to provide greater weatherability layer, the barrier film has provided feeding inhibition of Japanese beetles in trials conducted in blueberry and grape. Removal of the film after harvest increases marketability. This may be challenging for some types of fruit such as small fruit blueberry and raspberry.

The pyrethrum product Pyganic has has a 12-hour pre-harvest interval (PHI) and neem products such as Azadirect and Neemix have a zero-day PHI. These compounds are labeled for organic use, and have a short but effective impact on adult Japanese beetles with some mortality, some knockdown off the crop and some repellent activity.

High tunnels
Fruit production using high tunnels to protect fruit from rain has been found to significantly reduce the activity of Japanese beetles on fruit. As they will feed on fruit toward the end of tunnels in direct sunlight, Japanese beetle populations appear to be lower compared to field plantings.

Attract and kill
Japanese beetle monitoring can be conducted through the use of pheromone traps. Yet these traps are so highly attractive they tend to draw beetles in over long distances, attracting beetles from the surrounding landscape and increasing levels of infestation to crops. At this time mass trapping of beetles is not economically feasible in commercial fruit plantings and there is little evidence that this strategy will work to reduce beetle populations and crop injury.