According to a 2008 University of New Hampshire publication on Milky Spore disease, there are more reasons NOT to use this product than to use it in your home lawn. Milky spore has been around for decades and was the first biological control means for Japanese beetle grubs. Milky Spore comes in a powder and consists of a bacteria. The first reason not to use milky spore was the design, it was manufactured to control ONLY Japanese beetle grubs- unfortunately there are many more! Other turf damaging grubs in NH & VT include Asiatic beetles, European and masked chafers, June and May beetles and armyworms. So now you understand that even if milky spore could work, you would be controlling one grub out of many, not good odds.
The second major issue not to use milky spore is you must have Japanese beetles in your lawn in sufficient numbers to promote the bacterial population enough to expand and spread out in the soil. Therefore, if you do not have a large japanese beetle population, one where you would likely see damage- why bother? The third reason not to use milky spore in NH and VT is the fact that soil temperature must be between 60 and 70 degrees for 3 months. The high soil temperature necessary does not occur in our region and the bacteria can take over 4 to 5 years to build up, under ideal conditions, with a high population of Japanese beetles! Wow! You might want to go buy that lottery ticket today versus buying milky spore.
The Fourth reason not to use milky spore relates to how Japanese beetle grubs must ingest or eat the milky spore in the soil, not come into contact with, but eat it. To summarize, even under ideal conditions, purchasing and using milky spore disease is a serious waste of money and time especially since there are more effective organic/biological methods like Nematodes.
Nematodes are microscopic worms that are applied to the soil in a water spray. The nematodes then swim and attack the grubs while swimming in water between the soil particles. Nematodes will attack and destroy all of the grubs found in NH and VT listed above. They will also attack sod webworms! Since there is no “golden bullet”, Nematodes must be watered into the lawn or they will perish so that usually means applying them in the rain. The soil must have sufficient moisture content and you must target the grubs at the right life cycle stage. Having a professional apply Nematodes is the only true logistical option at this time, and our company does provide this service in our market area.
There are also a large range of new products on the market, some that do not even require a signal word because they are so applicator and environmentally friendly. In some states like Vermont- you must have a pesticide license even if you are applying organic products since it is considered a pesticide even if it is organic. Please keep in mind some organic products are just as dangerous or more so than some newer manufactured products. There are several key points to remember before using any “pesticide”, the first being is a treatment required and why? Secondly, what are the best material(s) to use for the job with the least impact to the environment and applicator. Do we need to treat the entire lawn or just a portion of it? Can we live with a small amount of damage and renovate later, only treating that one area or should we treat a larger area with a different product at a different time? These are all questions best left to the professional because without knowing insect or disease life cycles, product components, mode of action, and application method- things can go wrong real quick. This does not take into account the potential waste of material and use of a pesticide that should not have been used, regardless of composition. Doing the right thing, at the right time is harder to do than you may think.
I do hope you have learned something new today or perhaps confirmed something you already believed in regarding grub control. In any event, as fall fades into winter- be sure you are ready next spring because if you do have grubs- they will be waiting and you should have a game plan lined up this winter to address that very issue. Thanks for visiting my humble blog!
Be sure to the visit this UNH video link http://extension.unh.edu/agric/turf/media/lifecycl.htm