2014 SWD Survey
George Hamilton, Becky Sideman and I have set up an on line survey of spotted wing drosophila damage on New Hampshire crops, in 2014. Yes, it is very similar to last year’s survey. If you were a 2014 commercial NH grower of any crops that SWD attacks, please consider following this link and taking the survey. We will use the survey results to understand losses, the techniques growers are using, plan information programs for 2015, and support our grant applications. We’ll keep your responses anonymous. The survey should 10 minutes for most of you. Thank you for considering participation.
End of Thionex (Thiodan) Use
The manufacturer has agreed to a phase-out of Thionex, to reduce some worker safety concerns. On United States stone fruit, the last legal date to use it was July 31, 2012. On blueberries, the last date to use it is July 31, 2015. On strawberries, it can be used until July 31, 2016. It remains one of our most effective materials to control cyclamen mites in strawberries.
Deer Feeding on Strawberries
Deer sometimes feed heavily on strawberry plants, and one likely time for this is early in the season, when other foods are not very abundant. When we were working on a strawberry Pest Management Strategic Plan in December, I learned that some growers have success deterring deer feeding by applying either liquid manure around the perimeter of the block, or a seaweed product called Neptune’s harvest, directly sprayed on plants. I’d think of this as a nutrient management approach which could also reduce deer problems. Applying these materials at the wrong time could create other problems. In particular I think of food safety issues with the manure, if it were applied before harvest. But you knew that, right?
I was surprised to learn from a colleague that “Scent Wintergreen” is a spray adjuvant by Loveland Industries that is available to mix into the spray tank and mask objectionable odors. I had never heard of this, but used my internet browser to find both the label (which is very brief) and MSD sheet. I have seen no data on whether or not it alters the pesticide efficacy, or changes the rate of breakdown. But I know some of you tend to avoid certain pesticides on PYO crops close to harvest time because of the odor. The MSDS and label tell me it is a concentrated fragrance, a proprietary mixture of ingredients. I’ll let you look into it yourself, if you’re interested.
Two “New” Fungal Insecticides
I learned that there are two new insecticides registered with EPA, with the same fungus as the active ingredient. One product is called PFR-97 and the other is Preferal. Both were labeled back in 2012. PFR-97 is an OMRI-listed insecticide from Certis. It came to my attention in December, when we were discussing control options for black vine weevil in strawberries, but it is also labeled for some foliar insects on a range of greenhouse and outdoor crops. As with other fungal insecticides, direct contact with the product is important for control, and high humidity is needed too. Preferal is an OMRI-listed product by SePRO, with a very similar list of crops, sites and target pests. The active ingredient for both is Isaria fumosorosea Apopka Strain 97. Earlier the fungus was known as Paecilomyces fumosoroseus. I have seen no test data on these for black vine weevil, but I’m pleased to know we have more control options, especially for organic growers. BVW can be very difficult to control. When I searched the May 2014 NH pesticide registry list, I found Preferal was listed, but not PFR-97. Maybe both will get registered in the state this year.
Other New Insecticides
Closer is a new (reg mid-2013) chemical insecticide by Dow. Target pests have piercing-sucking mouthparts (aphids, scales, whiteflies, stinkbugs…) and crops include many vegetables, some tree fruit and some small fruit. It is in group 4C, along with ______. Yes, it was registered for use in NH in 2014. Coragen is a DuPont chemical insecticide in group 28. That means it has the same mode of action as the old botanical insecticide ryania. It is registered for a lot of caterpillars on vegetables, but I notice that under strawberry, it lists Japanese beetles (adults). I’ve had no experience with it. The labels I saw was from early in 2014. Yes, it was in the 2014 NH list of registered pesticides.
Captiva is made of plant extracts and oils, and is new, but I don’t see an OMRI symbol on it. Maybe that will come later? It is a Gowan product, and is listed to “repel and suppress” soft-bodied pests, like mites, psyllids, leafhoppers, caterpillars, thrips, whiteflies. Wow! The label has a really big list of crops, including some greenhouse and ornamental crops. It was new in 2014, so maybe it will get registered in NH this year.
Comments on Neonicitinoid Insecticides
There is increasing evidence that use of neonicitinoid insecticides may pose risk to pollinators. I’m not just talking about honey bees. We have over 100 species of bees in New Hampshire. In addition to the risk from being directly sprayed, or landing on just-sprayed surfaces, bees are at risk from some of these chemicals when they are applied to soil, and get absorbed by plant roots and systemically distributed inside the crop plants (including in pollen and nectar). Materials in this relatively new class (MOA group 4) include imidacloprid, acetampyrid, thiacloprid, thiamethoxam, clothianidin, dinotefuran, and others. The various chemicals in this group differ in the degree of risk they pose. Acetampyrid and thiacloprid are not particularly toxic to bees. Clothianodin, imidacloprid and thiamethoxam are highly toxic to bees. Obviously, the highly toxic ones could result in serious, immediate bee kill if they were applied to a blooming crop, or a crop with lots of weeds in bloom at the time of treatment. Regarding the risk from consuming contaminated pollen or nectar, the manner of application seems to affect risk. Direct foliar application after bloom seems to be less risky than soil (or seed?) treatment, which is often before bloom. These chemicals are pretty water soluble, so that increases the risk that they can eventually reach our rivers and lakes.
Pollinators are not the only ones at risk. Parasitoids and some aquatic insects are sensitive as well. European research suggests that extremely low levels (of imidacloprid for example) in surface waters leads to a reduction of water-dwelling invertebrates. Another problem is that most effects are not immediately obvious. We had a major bee kill in New Hampshire back when microencapsulated methyl parathion was first used (apparently improperly) in an orchard. The effect was immediately obvious…many hundreds of dead bees were found at hive entrances immediately after the spraying. But with the neonicitinoids, it is not immediate toxicity that is the major concern. Effects of low level exposure on some insects (especially bees, which are well studied) include problems in olfactory learning, navigation, locomotion, and immune systems. These don’t immediately kill the affected insects, but effects can still be serious (and lethal).
Reading the various research papers from both Europe and the USA, I’m nervous about relying on clothianodin, imidacloprid and thiamethoxam too heavily. Risks may be low in enclosed systems, like in many greenhouses. But they could be high in other situations, like soil applications to control white grubs or root weevils in strawberries. I’m looking for evidence to support my idea that neonics sprayed on apple foliage are less risky to pollinators if they are used after bloom has ended. (I’m not sure if that assumption is correct). So, if you’re planning on buying or using a material in this class (MOA group 4), please think about these points, and consider if there are safer alternatives. I’ll keep looking, too.