Japanese beetle on berry crops

Japanese beetle was first detected in Canada in 1939 and has been well established in parts of southern Ontario for some time. Residents of Hamilton-Wentworth and Niagara regions, as well as those near Port Dover and Windsor, are well acquainted with this pest. However, more and more fruit growers are finding out about Japanese beetles, as it continues to spread throughout Ontario.

The Canadian Food Inspection Agency has recently determined that all of Ontario and Quebec and parts of the Maritimes are now considered generally infested with Japanese beetle. This has a major repercussion for growers in Ontario who export plant material to areas where Japanese beetle is not found. These growers should consult the Canadian Food Inspection Agency Directive D-96-15 for details on areas affected by Japanese beetle quarantines and how to obtain certification for shipping plants to uninfested areas.

Japanese beetle adults are large, blocky beetles, with bright metallic green and brown colouring. They have 6 tufts of white hairs along their abdomen. Japanese beetle adults are voracious feeders. They skeletonize foliage and chomp on fruit of blueberries and raspberries. They feed on over 300 kinds of plants but many fruit crops are preferred, including raspberry, blueberry, peaches, grapes and plums and apples. The adults appear in late June and early July, about the same time raspberries begin to ripen. They are very active for about 6-8 weeks, and reach their peak in late July, when blueberries are ready for harvest. Feeding is most extensive on warm sunny summer days and is most likely to occur on plant parts exposed directly to the sun.

Larvae of Japanese beetle are one of several species of white grubs, and feed on roots of blueberries and many different plants, but especially on grasses. Most eggs are laid within a 7-10 day period and do not survive well in dry soils. Growers should carefully manage irrigation while eggs are laid or hatching, and especially avoid irrigation of grassy alleys between the rows. There are several chemical and biological control options to control Japanese beetle larvae in lawns and grassy areas. Although control of larvae is effective locally, fruit growers must be prepared to deal with adults that fly in from other areas.

Dr. Joseph Kovach, IPM coordinator at Ohio State University, recently spoke to growers at the Ontario Fruit and Vegetable Conference about Japanese beetles. His information suggests that Japanese beetles adults are fairly easy to control with insecticides, but if the beetles appear during harvest, there are few insecticide options where the days to harvest interval is adequately short. Some other interesting facts about Japanese beetle adults:

• Traps can be purchased to trap large numbers of Japanese beetle adults. However, these traps frequently attract more beetles than they catch, so they are not recommended in fruit plantings for beetle control.
  
• Plants such as Japanese maple, Norway maple, birch, pin oak, lindens and Virginia creeper are highly attractive to adult beetles and should not be planted near fruit crops.
  
• Certain varieties are more attractive than others to Japanese beetles. For example, the raspberry variety Prelude is much more attractive to beetles than Royalty, and the blueberry variety Duke is 3 times more attractive than Elliot.
  
• High tunnels have an effect on beetle populations. When beetle populations were compared on crops inside high tunnels to outside the tunnels, only 4% of the beetles were found in side the tunnels, compared to 96% captured on the same crops unprotected by high tunnels.

In Ontario, there are a few products labeled for Japanese beetle control. Organophosphate insecticides used to control other pests will often control Japanese beetles present at the time. On raspberries, Sevin XLR is labeled, and is very effective against Japanese beetle adults. However, the pre-harvest interval for this product on raspberries is 11 days, so it can't be used close to harvest when Japanese beetles are most likely to be active. It is also toxic to bees, so be careful when using it around fall-fruiting varieties which may be in bloom. In blueberries, Admire 240 F and Alias 240 WG are labeled for control of Japanese beetle larvae. These products are applied to the soil beneath the bushes and to the grassy alleys between rows. These are important products for keeping resident populations of Japanese beetles low, although they will do little to control adult beetles which fly in from elsewhere.