Friday, July 28, 2017

Japanese Beetles are Here in Abundance This Year....Now What?

The Village of Bellevue has fielded an extraordinary amount of calls regarding Japanese Beetles this year.  Yes, they are here, and they are hitting the Mid-West in full-force this year.  So now what do you do?
There are a couple of options for you if you want to take action in your garden and for your trees.  The Village does not spray or apply any insecticides on Village-owned street trees, so if your concern lies with the street trees in front of your property, you can do some things yourself if you choose, however you will need approval from the Forestry Division prior to doing so.  Should you desire to apply insecticide to the street trees in front of your property, the Village requires a tree-work permit (it is free) to be filed prior to any work being done on the Village's street trees.  The link for the permit is here. 

Vijai Pandian, the Brown County UW Extension Horticultural Agent/Educator, provided some very helpful tips in a recent article in the Green Bay Press Gazette on July 9.  For the full article click here.

Here are a few of your options to help lessen the effect of the Japanese beetles as per Vijai: 

Depending on the landscape settings, control options for adult Japanese beetles and their grubs varies.
1. Mature trees and shrubs have more tolerance to the feeding damage caused by the adult beetles and will leaf out again next year. No spray treatment is needed for mature woody ornamentals.

2. Small-size landscape plants such as roses, vegetable crops, strawberries and raspberries can be protected using floating row cover (white polyester spun bonded fabric) from afternoon until late evening hours. Drape the fabric over the plant and pin it to the ground. However, do not use the fabric on blooming vegetable crops such as pumpkins and squash, as they require bees for pollination.

3. Hand-picking and drowning the beetles in soapy water is another option to consider if populations are low in the garden.

4. Standard contact insecticides with an active ingredient containing carbaryl, imidacloprid, permethrin, bifenthrin, or Malathion are toxic to bees and should be sprayed on small-size woody ornamentals and perennials only after their blooming period. Read the product label for instructions and bee toxicity warning. An alternative product is Acelepryn, which is relatively new in the market and is known to provide good control on Japanese beetles as a foliar application and is less toxic to bees.

5. On fruits and vegetables, standard organic products such as neem oil and spinosad can be sprayed after the blooming period. Be sure to read the product label for its instructions, post-harvest interval period, and safety. For maximum control, spray during afternoon hours when the beetles are in peak activity. Repeat the application once every 5 to 10 days until mid-August.

6. Do not use Japanese beetle traps for control, as they will attract thousands of beetles towards your landscape and can result in more damage.

7. On turf, withhold your irrigation during the beetle’s active season. This will help in preventing beetles from laying eggs in your turf.

8. Schedule a preventive grub insecticide (active ingredient containing imidacloprid, halofenzide, clothianidin, or thiamethoxam) in your lawn before the end of July to prevent the eggs from hatching. It is best to use granular formulation. Before application, mow any flowering weeds such as clovers in your lawn to prevent bee toxicity. Or you can use acelepryn insecticide for a preventive application that is non-hazardous to bees. Immediately after application, schedule a light irrigation (1/8 inch) to leach the product into the thatch layer.

9. By mid-August, use a curative insecticide product (carbaryl, clothianidin, or trichlorfon) to control young grubs in your lawn. Mow any flowering weeds in your lawn before application and schedule a light irrigation after application.

For horticulture-related questions and advice, contact Brown County UW-Extension’s Horticulture Help Desk at 920-391-4615 or