safe pesticides for rose chafers and japanese beetles

Asked May 30, 2019, 2:38 PM EDT

We have some 1050 grapevines in northwest Antrim County. We have battled these bugs with various sprays and we have also spread milky spores (2 years). Got any ideas on products or techniques that are safe for environment? Also, is there a safe alternative to Roundup?

Antrim County Michigan

1 Response

Not sure what you mean by safe. I have worked with pesticides most of my life and I do not consider any pesticide safe whether they are synthetic,organic or natural occurring. These are products chosen because they kill things and are not safe. They are products that need to used carefully and all pose a risk to the environment.
Controling large insects like Rose Chafers and Japanese beetles usually requires a strong insecticide and repeated applications. These beetles are attracted to grapes and often aggregate where feeding has occurred attracted by an aggregation pheromone they release. Even if you kill the beetles more beetles will be attracted to the site by the pheromone. Treatment early to discourage the initial aggregations works good. I often recommend traps for these pests to distract them from the crop. Japanese beetle and rose chafer traps can be every effective attracting beetles from a long distance. They need to be placed well away from the grapes at least 150 ft. If the trap is placed in a grassy area put some milky spore there to kill the larvae in the soil. If you have a lot of beetles in the area you will need to empty the traps often. You can also spray strong insecticide such as Sevin (carbaryl) there to kill the beetles attracted to the trap.
Neem based products (Ecozin, AzaDirect, Agro-Neem, Trilogy, Neemix and others) can kill the beetles if you spray it on them and are effective for a few days. They can have a repellent action on adult beetles. They need reapplied every few days when pressure is high so you would be happy with weekly sprays but every 5 days might work and if you have traps close by you may be happy with the control.
Weed control is a perennial problem and Roundup is overused as a broad spectrum herbicide There are really no Broad spectrum post emergent herbicides I would consider safer than Roundup. I have several growers who just maintain a perennial sod in the vineyard. They believe all herbicides have an impact on the health of the vines. You need to be very careful trimming the grass around the trunks. If you use a weed eater be sure to put a guard around the trunk so you do not girdle the vine. I have another grower who uses a grape hoe to cultivate the ground under the trellis once or twice a year. That might not be a good choice for you depending on the slope of you site. Michigan State University Extension publishes a set of pesticide recommendations for Michigan fruit every year.
The Michigan Fruit Management Guide E154
It does include 'organic' and reduced risk pesticides.
Let me know if I can help with other questions