Efficacy of Additional Insecticides for Insect Pests in a MGVII Soybean Beaumont, TX 2005

Transcription

1 Efficacy of Additional Insecticides for Insect Pests in a MGVII Soybean Beaumont, TX 2005 Agronomic and Cultural Information Land preparation: Pulled beds (30 in. row width) on May 16 and cultivated beds prior to planting on Jun 7 Planting: Planted Pioneer 97B52 (MGVII) into Levac soil on Jun 9 After stand establishment, plots were hand-trimmed to 40 ft Plot size = 4 rows, 30 in. row width, 40 ft long with 4 replications Herbicide: s: Insect sampling: Harvest: Applied Dual II 2.5 pt/acre and First 0.75 oz/acre (PRE) on Jun 13 for early season weed control with a tractor-mounted spray tank and boom (30 gpa) Cultivation or herbicides not required for remainder of season Insecticide treatments (one application) were applied on Sep 1 as Lepidoptera larvae reached threshold levels. s applied with a CO 2 -pressurized hand-held spray boom (2- No. 2 cone nozzles on 30 in. centers, 50 mesh screens, 18 gpa) Pretreatment (PRE) samples collected on Aug 31 (20 sweeps/plot) with a 15 in. muslin sweep net Subsequent samples collected from the row adjacent to previous sampling 3 days after treatment (DAT) samples (20 sweeps/plot) collected on Sep 4 11 DAT samples (20 sweeps/plot) collected on Sep 12 Insect samples were transferred to plastic bags, frozen in the lab, and later identified and counted as time permitted. Prior to analysis insect data transformed using square root (x + 0.5) The later planting date (Jun 9) and the effects of Hurricane Rita resulted in a delayed and abnormal maturing of the soybeans. Foliage was stripped and pods were blown off. Some remaining pods matured and others remained green. Plots were not harvested for yield. See discussion below. 70

2 Discussion Lepidoptera larvae reached threshold levels by Sep 1 (soybeans at R4/5 growth stage). Velvetbean caterpillar (VBC) was the predominant species with green cloverworm (GCW) and soybean looper (SL) occurring in fewer numbers. Due to deterioration of insect samples with the loss of power during Hurricane Rita, Lepidoptera species (VBC, GCW and SL) were not analyzed separately but lumped into a total. Insecticide treatments (one application) were applied on Sep 1 following pretreatment sampling (20 sweeps/plot) on Aug 31. Three days after treatment (DAT) Asana XL, Mustang Max, Karate Z, Baythroid 2, Prolex, Intrepid 2F and Orthene 90S provided excellent control of Lepidoptera larvae (Table 1). These products also kept larvae counts at or near zero through 11 DAT. All three rates (low, mid and high) of both Mustang Max and Intrepid 2F performed equally well. Methyl parathion and the high rate (0.065) of KN128 also controlled Lepidoptera larvae well through 11 DAT (Table 1). All three rates of Steward SC and the low and mid rate of KN128 were less effective but performed statistically as well as methyl parathion 3 DAT. Addition of MSO surfactant to the low rate of KN128 did not improve efficacy (Table 1). At 11 DAT Lepidoptera larvae counts in untreated plots appeared to be declining naturally. Southern green stink bug (SGSB), red-banded stink bug (Piezodorus guildinii, PG) and phytophagous brown stink bugs (BSB) were present in low numbers throughout the sampling period which seems to be typical of a later planting date with a later maturing soybean such as a MGVII (Tables 2-4). Although some treatments showed a statistical decline in total stink bugs 3 DAT compared to the untreated, it is probably not useful to draw any conclusions on stink bug efficacy based on the initial low populations (Table 5). Threecornered alfalfa hopper (TCAH) were uniformly present throughout the test area but in relatively low numbers prior to application of insecticide treatments. Populations continued to increase 3 and 11 DAT in some treatments but seemed to be controlled and/or held in check by methyl parathion, Asana XL, Mustang Max (all three rates), Karate Z, Baythroid 2, Prolex and Orthene 90S (Table 6). Steward SC, KN128 and Intrepid 2F were not effective in reducing TCAH populations. Addition of MSO surfactant, however, may have enhanced the efficacy of KN128. These conclusions on TCAH efficacy are somewhat generalized, but may help identify those insecticides which may potentially control TCAH. See Tables 1-6 below. 71

3 Table 1. Efficacy of additional insecticides for control of Lepidoptera larvae in soybean. Beaumont, TX No. Lepidoptera larvae a /20 sweeps Untreated a 5 a Methyl parathion 1.0 pt/acre 12 3 bcd 2 abc Asana XL e 0 d Steward SC b 2 abcd Steward SC b 4 a Steward SC bc 2 abcd KN b 3 ab KN bcd 3 a KN cde 2 abcd KN128 + MSO % v/v 15 6 b 4 a Mustang Max de 1 bcd Mustang Max e 0 cd Mustang Max de 1 bcd Karate Z e 1 bcd Baythroid e 1 abcd Prolex e 0 d Intrepid 2F 4 oz /acre 16 1 e 0 d Intrepid 2F 6 oz/acre 13 1 e 0 d Intrepid 2F 8 oz/acre 18 1 e 0 cd Orthene 90S de 1 bcd a Sum of velvetbean caterpillar, green cloverworm and soybean looper Means in a column followed by the same or no letter are not significantly different () at the 72

4 Table 2. Efficacy of additional insecticides for control of southern green stink bug in soybean. Beaumont, TX No. southern green stink bug a /20 sweeps Untreated d 2 Methyl parathion 1.0 pt/acre 0 0 d 1 Asana XL cd 2 Steward SC cd 0 Steward SC cd 0 Steward SC bc 1 KN bcd 1 KN d 2 KN abc 1 KN128 + MSO % v/v 0 0 cd 1 Mustang Max cd 0 Mustang Max cd 0 Mustang Max d 0 Karate Z cd 1 Baythroid cd 1 Prolex d 1 Intrepid 2F 4 oz /acre 0 1 cd 0 Intrepid 2F 6 oz/acre 0 2 ab 1 Intrepid 2F 8 oz/acre 0 2 a 1 Orthene 90S cd 0 a Nymphs + adults Means in a column followed by the same or no letter are not significantly different () at the 73

5 Table 3. Efficacy of additional insecticides for control of red-banded stink bug in soybean. Beaumont, TX No. red-banded stink bug a /20 sweeps Untreated Methyl parathion 1.0 pt/acre Asana XL Steward SC Steward SC Steward SC KN KN KN KN128 + MSO % v/v Mustang Max Mustang Max Mustang Max Karate Z Baythroid Prolex Intrepid 2F 4 oz /acre Intrepid 2F 6 oz/acre Intrepid 2F 8 oz/acre Orthene 90S a Piezodorus guildinii (nnymphs + adults) Means in a column followed by the same or no letter are not significantly () different at the 74

6 Table 4. Efficacy of additional insecticides for control of phytophagous brown stink bugs in soybean. Beaumont, TX No. phytophagous brown stink bugs a /20 sweeps Untreated cd Methyl parathion 1.0 pt/acre d Asana XL abcd Steward SC d Steward SC bcd Steward SC abcd KN d KN cd KN a KN128 + MSO % v/v abcd Mustang Max abcd Mustang Max ab Mustang Max abc Karate Z bcd Baythroid abcd Prolex d Intrepid 2F 4 oz /acre d Intrepid 2F 6 oz/acre d Intrepid 2F 8 oz/acre d Orthene 90S bcd a Nymphs + adults Means in a column followed by the same or no letter are not significantly different () at the 75

7 Table 5. Efficacy of additional insecticides for control of total stink bugs in soybean. Beaumont, TX No. total stink bugs a /20 sweeps Untreated abc 3 Methyl parathion 1.0 pt/acre 1 0 e 2 Asana XL cde 4 Steward SC abcde 1 Steward SC cde 1 Steward SC abcde 2 KN abcde 1 KN e 2 KN abc 4 KN128 + MSO % v/v 1 1 cde 2 Mustang Max bcde 3 Mustang Max e 2 Mustang Max de 3 Karate Z bcde 2 Baythroid bcde 3 Prolex cde 1 Intrepid 2F 4 oz /acre 1 2 abcd 1 Intrepid 2F 6 oz/acre 1 3 a 2 Intrepid 2F 8 oz/acre 2 3 ab 1 Orthene 90S cde 2 a Sum of southern green, red-banded, and phytophagous brown stink bugs (nymphs + adults) Means in a column followed by the same or no letter are not significantly different () at the 76

8 Table 6. Efficacy of additional insecticides for control of threecornered alfalfa hopper in soybean. Beaumont, TX No. threecornered alfalfa hopper a /20 sweeps Untreated cdef 19 abc Methyl parathion 1.0 pt/acre 10 7 cde 4 bcdef Asana XL ef 4 efgh Steward SC abc 11 cdefg Steward SC cdef 13 bcde Steward SC abc 20 abc KN bcd 12 cdef KN ab 15 abcd KN abc 13 bcdef KN128 + MSO % v/v 5 10 abc 7 defgh Mustang Max ef 2 h Mustang Max ef 1 h Mustang Max def 2 h Karate Z f 5 efgh Baythroid ef 3 gh Prolex ef 4 fgh Intrepid 2F 4 oz /acre 7 19 a 24 ab Intrepid 2F 6 oz/acre 7 16 ab 18 abc Intrepid 2F 8 oz/acre 6 20 a 27 a Orthene 90S f 8 defgh a Nymphs + adults Means in a column followed by the same or no letter are not significantly different () at the 77