IR-4 Ornamental Horticulture Program Research Report Cover Sheet

Transcription

1 IR-4 Ornamental Horticulture Program Research Report over Sheet Researcher(s) Richard owles Affiliation: onnecticut Agricultural Experiment St 153 ook Hill Road P.O. Box 248 Windsor T PhoneNumber: richard.cowles@po.state.ct.us Trial: 2007 T ProjectTitle: White Grub & Root Weevil Efficacy Protocol #: PR# Research Target rop/plant Product EPA Reg. # Production Site Status Black Vine Weevil BAS 320i - Field ontainer Black Vine Weevil Metaflumizone elero 16WSG BASF Field ontainer lothianidin Arysta Black Vine Weevil Discus Imidacloprid + yfl OHP Field ontainer Black Vine Weevil DPX-E2Y45 - Field ontainer hlorantraniliprole Dupont Black Vine Weevil Flagship 25WG Thiamethoxam Syngenta Field ontainer Black Vine Weevil Metarhizium anisop - Field ontainer Black Vine Weevil Metarhizium anisop Safari 20SG Novozymes Bi Field ontainer Dinotefuran Valent Black Vine Weevil Talstar NG 279- Field ontainer Bifenthrin FM

2 New insecticides for control of black vine weevil larvae in container-grown plants Richard S. owles onn. Agric. Expt. Station, Valley Lab Windsor, T Black vine weevil (BVW) is a serious pest of ornamental nursery crops (field and containergrown), vineyards, strawberries and hops. This study, sponsored by the IR-4 Program, used potted strawberries as a model system to determine which insecticides would provide protection against BVW larvae. Special attention was paid to determine whether there was a dose-response for two new insecticides (chlorantraniliprole [DPX E2Y45] and metflumizone [BAS 320]), to compare neonicotinoids, and to compare preventive preplant incorporation into potting media with curative drenches targeting 3 rd instars. Strawberry daughter plants were taken from research plots at the Valley Laboratory on 16 Nov ultivars used were 'Allstar', 'Annapolis', 'Darselect', 'Idea' (two replicates), and 'Jewel'. Previous data indicated that there are no differences among healthy plants of several strawberry cultivars regarding suitability for BVW larval development; however, cultivars were kept separate and this experiment was blocked by cultivar (six replicates). Prior to planting, the entire strawberry plant was dipped into a 1:10 dilution of household bleach, and allowed to sit with a film of bleach solution for 20 min prior to thorough washing. This procedure disinfests plants of any insect pathogenic nematodes adhering to the roots. After thorough washing, plants were potted into #1 nursery containers (2.7 L per pot) using pretreated media or the standard medium, which consisted of a 1:2:1 mixture (by volume) of leaf compost: pine bark chunks: peat. A 500 ml aliquot of medium was dried in an oven to determine that its dry bulk density was 257 kg m -3 (433 lb/ cubic yard). Preplant incorporations were mixed on 10 Nov in a concrete mixer, with a volume of medium to fill 6 pots mixing for 2 min with insecticide. Talstar 0.2G was incorporated by adding granular product while the concrete mixer was rotating. For sprayable products, sufficient material (DPX E2Y45, BAS 320i) to treat 6 pots was diluted into 100 ml of water, and then sprayed onto the surface of the medium while the mixer was rotating. Metarhizium anisopliae was applied to potting medium on 9 Jan by removing plants from pots, mixing spores with the medium in the concrete mixer, and repotting. Early curative drenches were applied on 15 March, using an application volume of 70 (DPX E2Y45 treatments) or 100 ml per pot (all other drench treatments) of product diluted in tap water. Plants were watered to move the products into the medium 24 h following application, taking care not to cause excessive leaching. Plants were grown in a greenhouse maintained with a minimum temperature of 15 (60 F) and with automatic daily overhead mist irrigation. Black vine weevil eggs were obtained from a colony at the Valley Laboratory. About 200 adults were enclosed in a 20 L plastic bucket with yew foliage, and eggs were collected by shaking foliage on a weekly basis. Sufficient eggs were not available on any one collection date, and so pots were repeatedly infested 9 Jan - 6 Feb until there were 45 eggs added per pot. Eggs were placed 1 2 cm deep in the soil, close to the crown of the plant. Larvae were counted on 16 and 17 April by sifting through the potting media shaken from the strawberry root system. Data required some manipulation prior to analysis. Several treatments

3 had no recovery of weevils. When this occurs zero-variance treatments prevent establishing homogeneity of variance. Furthermore, multiple zero-variance treatments can downwardly bias the common variance estimate in AOV, which is inappropriate for conducting mean separation for the remaining treatments. To remedy this problem, only one representative treatment with zero counts was left in the analysis. Following this step, square-root transformation of the data provided homogeneous variances. Replicate 1 in nearly all the treatments (with one exception) had zero counts, so this replicate was deleted from the analysis of variance. Because there were no significant block effects (cultivar had no effect), the final analysis used a completely randomized design. Results and Discussion Recovery of BVW larvae was about ~10%, relative to the number of eggs, for ineffective treatments in this study. Typically, I expect about 40 60% recovery of larvae relative to the number of infested eggs. However, the treatment responses were highly significant (F [8,36] = 2.76, P = ). It is notable that all of the preplant potting mix incorporation treatments of synthetic insecticides, including the positive control standard of Talstar 0.2G, were completely effective. There was no discernable response to dosage with the metflumizone product, because all tested concentrations caused complete mortality. Further tests will need to investigate lower dosages. Although the chlorantraniliprole pretreatment of media was completely effective, only the higher dosage of this product applied as an early curative drench suppressed the BVW population. An even higher dosage of this product used as a curative drench may provide acceptable control. Neonicotinoid products performed poorly against BVW larvae as early curative drench treatments; none was significantly different than the untreated check. Interestingly, Discus, a combination of cyfluthrin and imidacloprid, has performed better (50 75% population reduction, RS unpublished data) in a previous study, which used this product in a higher volume drench. Either there was poor mobility of the insecticides used in the drench procedure used in this study, or poorer within-pot distribution of active ingredient. The inadequacy of most drench treatments is in contrast to the metflumizone drenches, which were completely effective. It will be important to determine whether metflumizone is more mobile in potting media than the other products, and to determine the lowest effective dosage of this product for protecting plants from black vine weevil larvae. Results with Metarhizium anisopliae were disappointing. Other tests (including mine) have provided variable results, ranging from lack of control to complete elimination of BVW larval populations. The cool temperatures and poor quality inoculum may have contributed to its ineffectiveness.

4 Table 1. Efficacy of products used for control of black vine weevil larvae. Treatment Product Dosage Active ingredient No. of ontrol (%) ode (mg/pot) Larvae * 18 Untreated check abc - Preplant mix 2 DPX E2Y45 5 ppm d DPX E2Y45 10 ppm d DPX E2Y45 20 ppm d BAS320 E 25 ppm d BAS320 E 50 ppm d BAS320 E 100 ppm d BAS320 E 200 ppm d Talstar 0.2G 10 ppm d Metarhizium anisopliae spores/l a 0 urative drench 1 DPX E2Y fl oz/100 gal a 0 15 DPX E2Y fl oz/100 gal cd 75 9 BAS320 S 50 ppm d BAS320 S 100 ppm d Arena 50 WDG 1.28 oz/ 100 gal a 0 12 Safari 20 SG 24 oz/ 100 gal bcd Discus 13 fl oz/100 gal ab 0 14 Flagship 25 WDG 8 oz/100 gal ab 0 * Means followed by the same letter do not significantly differ (Fisher's protected LSD test, P < 0.05). Expressed in µl per pot. This amounts to 1.00 mg of imidacloprid and mg cyfluthrin per pot.

5 Treatment Replicate Weevil 2 Weevil 3 Weevil 4 Weevil 5 Pupae Total

6 Treatment Replicate Weevil 2 Weevil 3 Weevil 4 Weevil 5 Pupae Total

7 Treatment Replicate Weevil 2 Weevil 3 Weevil 4 Weevil 5 Pupae Total