Final Report for FNE99-258
Note to readers, attached is the complete final report for FNE99-258
Tarnished Plant Bug (TPB) is an active feeder on flowers of every sort, and has a devastating impact on strawberries. When the nymph of TPB feeds on the just opened strawberry blossom, it interferes with the pollination of that fruit. TPB damaged fruit are button shaped and seedy, sometimes suitable for jam but frequently of no value at all. It is common for the early fruit to be fine, but the later portions of the crop to be ruined. The hot spring and early summer weather this year exacerbated TPB damage.
The standard control for TPB is Malathion, an organophosphate and a potent inhibitor of the nervous system. Many farmers would like to learn of a method to control TPB without having to work with this compound, or as a part of an effort to grow strawberries organically.
For this propject we tested four different methods. We tried floating row covers, garlic sprays, vacuuming, and releases of the predator wasp Anaphes iola.
The floating row cover encouraged earliness, which in itself is a good technique to limit TPB damage. On later varieties, though, there seemed to be enough TPB emerging from the mulched ground under the row cover to mess up the fruit badly.
Garlic barrier spray, although labeled for TPB, had no effect of the TPB population. Perhaps it needs to be applied more frequently, beginning very early in the season, and at higher rates. But in our trials it was ineffectual.
Vacuuming showed promise. Using a backpack gas powered vacuum over the row, TPB counts would drop to an acceptable level. The problem was that it would rise back up again quickly. Perhaps daily usage would make a difference.
The release of the predatory wasp Anaphes iola brought TPB counts down, but not low enough to prevent major economic damage to the crop. Yields certainly would have been worse without their release, but this partial control comes at a high cost, and makes this a questionable option.
As of Spring 2003, this option is no longer available as the lab producing this beneficial insect has quit.
Organic strawberries have some inherent challenges economically, not the least being TPB. Current organic methods have yet to control this insect by killing the nymphs at the time that the blossoms are susectible to feeding damage. The latest strategies, as of Spring, 2003, are the use of row covers to push the earliness of the bloom ahead of the crest of the TPB nymph population, and the use of Beauravia bossiana as a biocide against the nymphs. Neither of these techniques are consistently successful. Organic strawberry production is a valuabe crop in a mix on a farm that needs early summer income, wants to build a reputation, or has a CSA to satisfy. The higher prices for OG strawberries are not quite high enough to compensate for the loss of production to TPB.
We have concluded that the best options for TPB control in organic strawberry production are cultural. Very thorough weed control, and very careful mowing of the field edges help limit TPB food sources before blossoming, and help suppress their numbers. Crop rotation, including moving the crop as far as possible on the farm, is essential. Also to consider is going in and out of strawberries over a period of years rather than cropping them every year. TPB remains the biggest stumbling block to being able to crop strawberries continuously as do our chemical using neighbors.
None of the methods we tested during the 2000 growing season were adequate to repeat. I have move on to the use of b.b. in the form of Naturalis L an OMRI approved fungal spray. I will also continue with soil building and weed control practices as a deterrent to TPB.