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Cross-species pest management with parasitic nematodes

Cross-species pest management with parasitic nematodes
March 10, 2014 06:54PM
One area of research that is really active right now is using parasitic nematodes to control insect pests in a sustainable manner. I am posting this here rather than under each pest species that might be managed this way. Separate research projects are exploring using them to control borers, including apple and peach tree borers, plum curculio, and codling moth. We are hoping to figure out timing and nematode species that will help reduce all of these pests in our orchard. Steinernema feltiae has been used against apple borer and codling moth, and shows promise infecting plum curculio larvae in lab conditions (though the species S. riobrave appears to be more effective, even in the northeast; see the Shapiro-Ilan reference below). We began last year by spraying for apple and peach borer in late August; the research projects followed up with another spray 3 weeks later; we decided to do a later spray that could control codling moth as well, which requires a window above 46F and very damp for 12-24 hours or more after spraying after the codling moth larvae are on the ground. We are still trying to figure out the best time to spray for plum curculio, based on when they are in the ground as larvae or adults, and what life stage the nematode species prefers. Any thoughts on timing for PC welcome.
-Jen from Bear Swamp Orchard

Reference on field trial of nematode control of PC in Belchertown, MA and WV:
Shapiro Ilan, D.I., Wright, S.E., Tuttle, A.F., Cooley, D.R., Leskey, T.C. 2013. Using entomopathogenic nematodes for biological control of plum curculio, Conotrachelus nenuphar: Effects of irrigation and species in apple orchards. Biological Control. 67:123-129.

Reference on controlling codling moths with nematodes:
Kienzle et al. 2010. Three years experience with entomopathogenic nematodes for the control of overwintering codling moth larvae in different regions of Germany. Proceedings of Ecofruit. [www.ecofruit.net]
(note: this Ecofruit conference had many papers on this topic, including this one)
Re: Cross-species pest management with parasitic nematodes
March 11, 2014 02:04PM
It is exciting to me that people are making progress with this approach. I tried it in a SARE farmer grant project in 1993-4 without success, but I was probably using the wrong species. I targeted the time in July when PC were pupating under the trees. The report is at:
[mysare.sare.org]

In NY, Art Agnello and Elson Shields are currently working on this.

Good luck!!

Hemlock Grove Farm
Zone 5 in New York
I have been in touch with David Shapiro who is researching the effect of nematodes on plum curculio, among other things. He says the species S. riobrave, which was the most successful against PC, is not commercially available currently, but may be sometime in the near future. Meanwhile, the runner up species S. feltiae is widely available, and is also the species used against codling moth in trials in Germany. Dr. Shapiro also found the sticker Shatter-Proof to improve efficacy when using nematodes to control borer, since it protects them from UV damage and desiccation and greatly increases how long they survive.

One thing to note about using nematodes is they are totally worthless if the conditions aren't correct. It needs to be damp for as long as possible (12-24hr minimum) and in the right temperature range for the species being used or you get zero survivorship and might as well have sprayed water. They recommend a fairly high-water mix since the water helps wash the nematodes into the soil where they will be more likely to survive. In Germany they had the best control of codling moths when they sprayed essentially during rain. I can imagine some years where there is never a window of suitable rain with mild temperatures, especially for codling moth since that needs to be sprayed as late as possible when all the codling moth larvae have dropped. We will just have to see how we can manage this tool.

Jen from Bear Swamp Orchard
Ashfield MA, zone 4-5



Edited 1 time(s). Last edit at 03/11/2014 03:12PM by Steve Gougeon.
Re: Cross-species pest management with parasitic nematodes
February 28, 2015 07:28PM
Timing being key, I like to hear feedback on the following pest species that pupate in the soil. And for these purposes, the trunk zone can be considered part of the soil ecosystem, provided we give nematodes a "mudpack" in getting launched above ground.

Plum Curculio leave the fruitlet behind when these come off the tree at June drop. This typically occurs 3 to 4 weeks after petal fall. The larvae may linger in the fruitlet for a week or so before crawling into the soil. Second generation adults subsequently emerge in August in staggered fashion. This window seems obvious: apply nematodes about a week after June drop. It's the month of July when PC can be found in the soil and not at any other point in the year.

European Apple Sawfly leave the fruitlet behind when these come off the tree at June drop. The pupae will be the soil until the next spring, when adults emerge prior to bloom. Noting that the "larvae-to-pupae transition" seems most efficacious for nematodes tells me that a PC application a week after June drop also aptly applies to EAS.

Apple Maggot Fly emerges in staggered fashion from mid-June through mid-August, laying eggs into just-ripening fruit, with summer varieties being targeted first followed by mid-season apples. Early drops often are infested. AMF larvae are in the fallen fruit for 3 to 9 days before crawling into the soil. Pupae are in the ground beneath our trees essentially from September through May, give or take. Nematode application for AMF (targeted beneath especially infested varieties) might best be applied in mid-September on early apples and then again in mid-October on midseason apples. Fast forward this for Cherry Fruit Fly species, say a week to two after completing the cherry harvest.

Peach Tree Borers can be targeted once the eggs are laid in early to midsummer, as these moth larvae will be chewing the cambium from that point on through fall and winter and into early spring. Front end application in August stops the damage. The eggs of Apple Tree Borers hatch the month before harvest, with these beetle grubs then chewing the cambium for the next two years. September and October are the ideal time to "grub out the grubs" with a sharp knife provided you see each and every entry hole. I'm more inclined toward using botanical trunk sprays of pure neem oil to deter egglaying in early summer, with subsequent applications to douse the soil line at the base of the trunk in fall and early spring to break the molting cycle of RHAB. The nematode card could be useful in cleaning up a heavily-infested planting. Shatter-Proof is a purchased product that can be used instead of biodynamic tree paste (being one "mudpack" variant) to give nematodes a chance to work inward on the trunk surface.

Codling Moth has been indicted in nematode research and that's great. These moth larvae will spend the winter in diapause, and are just as likely to be found curled into bark crevices as tucked into the soil at the base of understory plants. Fall application after harvesting all varieties on a warm day seems right for the nematode plan if things got out of hand in the growing season. Target first-generation larvae by other means in the fruit set window ... and you keep the proverbial worm out of the apple come harvest time.

Lost Nation Orchard
Zone 4b in New Hampshire
I attended a workshop through Cornell extension at Redbyrd orchard last summer about another nematode approach. Cornell researchers are experimenting with inoculating orchards with a parasitic nematode native to NY, that persists for decades at least, after one application. This is not commercially available but the workshop covered growing these nematodes, so they could send us a starter kit, we could grow the number of nematodes we needed, and apply them in our orchards. It takes a few years for the nematodes to infiltrate all the soil, and they were mostly thinking about the effect on PC. But, they would be present and active throughout the season so would presumably have some effect on any soil pupating insects that are vulnerable to these parasites. They thought because CM mostly overwinter on bark it would not have an effect on them, nor would it likely impact borers which are also in the trunk where nematodes can't maintain a population. We will be applying these nematodes this spring and see what happens to pest pressure. Steve and perhaps Eric from Redbyrd? will be at the Hawley growers meeting next week, so for those of you who will be there they can share info about this program.

Jen

Bear Swamp Orchard
Zone 4b in Massachusetts
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