Cost Benefits of Common Insecticide Practices Used to Prevent Soybean Pest Problems in Delaware

Final report for ONE19-344

Project Type: Partnership
Funds awarded in 2019: $28,221.00
Projected End Date: 12/31/2021
Grant Recipient: University of Delaware Cooperative Extension
Region: Northeast
State: Delaware
Project Leader:
Dr. David Owens
University of Delaware
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Project Information

Summary:

Soybean is a major crop grown on the Delmarva Peninsula and is habitat for hundreds of species of arthropods, most of which are beneficial or inconsequential to the crop. While a few species are pests, they are usually not present at damaging levels, and crop losses from insect pests are typically low. However, it is not uncommon for farmers to mix an insecticide with other planned chemical applications due to the perception that it will prevent a later application. Strip trials were installed on various participating farmer fields in 2020 and 2021 to examine the impact such applications have on the seasonal pest populations and on yield to determine if on a large scale these applications prevent risk of follow up treatment and if they confer a yield benefit to offset the cost of insecticide product cost in the tank mix. Most fields in 2020 were double crop soybean, applications went out with late herbicide or with reproductive stage fungicide applications. In 2020 none of the fields reached the insect pest complex threshold, with a possible exception of one site that had a fairly high but brief count of green cloverworm. Field activities were expanded to additional farmers in 2021 and strips were replicated in fields. Defoliators were generally significantly reduced in the treated strips, especially among green cloverworm and grasshoppers. Some slight differences were detected with regards to bean leaf beetle and stink bug populations, although both pest groups did not exceed threshold. Indications from this project suggest that in typical scenarios, prophylactic insecticide application, especially early in the crop cycle is yield neutral and is not justified to the extent that they are applied.  Project activities and results were shared with farmers and interested stakeholders through presentations at county meetings and Delaware Agweek.

Project Objectives:

The objectives of this project were to 1)Demonstrate under which circumstances and to what extent prophylactic insecticides effectively prevent the need for follow up insect pest chemical applications, 2) Determine if prophylactic insecticide use results in a positive yield benefit, and 3) gather large, field-scale data to inform extension recommendations. 

Introduction:

Many farmers mix an insecticide in with applications that are already being applied to the crop, usually a vegetative stage herbicide and a reproductive stage fungicide. Even though such applications are cheap, they may not be timed in a way that will result in a yield advantage over using an IPM approach. Insecticide applications can disrupt the in-field ecology, removing natural enemies, and potentially permitting pest populations to increase. Insect pest populations can be patchy in the mid-Atlantic and often do not exceed typical economic thresholds which take into account yield loss equivalent to control costs.

The most common active ingredient, lambda-cyhalothrin, can cost as little as $2 per acre in product to apply, but, when extrapolated out to the estimated treated area (37.6% acreage in 2017), could be nearly a $100,000 input which may not be efficacious or economically advantageous. Soybeans are especially resilient to pre-reproductive stage defoliation. The most common herbivorous insects that could impact the crop during the vegetative stages include bean leaf beetle, thrips, spider mites, and green cloverworm, but vegetative stage soybean can tolerate as much as 50% defoliation without incurring significant yield loss. University thresholds are conservatively set at 35%. Double-crop soybean fields cannot compensate for defoliation to the extent that full season bean fields can, thus there can be differences in crop responses and pest dynamics between full and double crop soybean when considering a prophylactic insecticide.

To investigate risks and returns associated with prophylactic insecticide usage, participating farmers installed strip trials with and without insecticide tank mixes when performing other chemical application inputs. Plots were sampled throughout the growing season to assess pest and beneficial insect abundance and yield data were collected from yield monitors and weigh wagons.  By conducting on-farm research with field size plots and from numerous locations on Delmarva and planting windows (full season and double crop), a strong extension message about the utility or disadvantage of prophylactic insecticides can be delivered to area farmers, potentially saving input costs that affect farm and environmental sustainability.  

Cooperators

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Research

Materials and methods:

2020

Five farmers participated in the study and applied single insecticide (WarriorII, 1.92 fl oz/acre)-treated strips in fields when applying herbicide (4 farmers) or fungicide applications (2 farmers). One farmer applied insecticide to paired adjacent fields instead of strips within fields. Treated and non-insecticide treated plots were sampled weekly using sweep nets (4-5 10-sweep samples per plot) and visual defoliation estimates until soybeans began senescing at the end of the season. Yield data in 2020 was collected from farmer yield monitors. Most fields sampled in 2020 were double crop soybean fields which were expected to have greater numbers of pest insects and less ability to compensate for defoliation. Over all fields sampled, samples from each location were averaged by number of sweep samples taken. The difference between untreated strips and pyrethroid treated strips were tested against a hypothesized mean value of 0 (no difference).  A negative number means that there were, overall, greater numbers in the Untreated, and positive numbers mean there were greater numbers in the Pyrethroid treated strips.

2021

In 2021, 8 cooperators (3 of which participated in the 2020 trial) installed pyrethroid treated areas of their fields during vegetative herbicide applications. Seven of the sites had replicated strips and were scouted during the course of the season. At each of the seven sites, a minimum of three treated strips were paired with three untreated strips. Strips were treated with Warrior II at 1.92 fl oz/acre. Strips were sampled weekly for beneficial insects and insect pests. In each strip, a series of four 10-sweep samples were collected and at least during the first week after application, 10 upper canopy leaflets from four locations in each strip were also collected to record thrips, mites, and pirate bugs. Each strip was geo-referenced. Useable yield data was collected from 6 sites. At three sites, yield data was collected by harvesting a full combine header width for 800 - 1600 feet and transferring beans to a weigh wagon. At one site, total yield was taken from paired field blocks, and at two sites, yield monitor data was analyzed such that 1-2 complete header passes in the center of the treated strips were selected for yield calculation. 

 

Research results and discussion:

2020

Insect pests at all of the five trial locations were generally low with the exception of one site in Harbeson, DE. At this site, green cloverworm populations increased significantly three weeks after treatment in the untreated check plot. Defoliation approached 10%. The cooperator decided to make an insecticide application. Useable yield data was collected at three of the five sites. The overall difference was -0.7 bushels, but this was not statistically significant. 

2020 Insect Scouting Data

Harbeson, DE July 1

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0.25 ± 0.2

0.3 ± 0.2

0.4 ± 0.2

0.3 ± 0.1

0

0

0

0

0

Pyrethroid

0

0.4 ± 0.3

0.4 ± 0.3

0

0

0

0

0

0

T

P = 0.20

P = 0.80

P = 1.0

P = 0.08

 

 

 

 

 

July 9

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

1.4 ± 1.0

4.8 ± 0.3

1.5 ± 0.5

0.2 ± 0.1

0.1 ± 0.1

0.2 ± 0.2

0.1 ± 0.1

0

0

Pyrethroid

0.4 ± 0.2

0.3 ± 0.3

0.3 ± 0.1

0.1 ± 0.1

0.1 ± 0.1

0.1 ± 0.1

0

0

0

T

P = 0.38

P = 0.01

P = 0.09

P = 0.55

P = 1.0

P = 0.67

P = 0.36

 

 

July 17

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

1.1 ± 0.4

25.8 ± 1.9

0.3 ± 0.1

0.6 ± 0.4

0.5 ± 0.3

0.1 ± 0.1

0.2 ± 0.1

0

0

Pyrethroid

0.8 ± 0.5

12.4 ± 2.4

0.8 ± 0.4

0.3 ± 0.1

0.5 ± 0.2

0

0.2 ± 0.2

0

0

T

P = 0.72

P <0.01

P = 0.26

P = 0.45

P = 1.0

P = 0.36

P = 1.0

 

 

August 3

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0.2 ± 0.1

1.3 ± 0.2

0.2 ± 0.1

0

0

0

0.2 ± 0.1

0

0

Pyrethroid

0.2 ± 0.1

1.8 ± 0.4

0.1 ± 0.1

0

0

0

0.1 ± 0.1

0

0

T

P = 1.0

P = 0.22

P = 0.55

 

 

 

P = 0.55

 

 

August 14

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

1.0 ± 0.5

0.7 ± 0.3

0

0

0

0

0.2 ± 0.1

0

0

Pyrethroid

0.3 ± 0.1

1.3 ± 0.5

0

0.3 ± 0.3

0

0

0.3 ± 0.1

0.2 ± 0.1

0

T

P = 0.20

P = 0.28

 

P = 0.36

 

 

P = 0.60

P = 0.17

 

August 21

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

1.5 ± 1.0

2.3 ± 0.5

0

0

0

0

0.1 ± 0.1

0.2 ± 0.2

0

Pyrethroid

3.7 ± 1.7

1.7 ± 0.5

0

0

0

0

0.5 ± 0.2

0.3 ± 0.2

0

T

P = 0.30

P = 0.45

 

 

 

 

P = 0.08

P = 0.50

 

August 27

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

1.2 ± 0.3

0.9 ± 0.5

0

0.1 ± 0.1

0

0.2 ± 0.2

0.2 ± 0.1

0

0

Pyrethroid

1.4 ± 0.8

0.6 ± 0.2

0

0.2 ± 0.1

0

0

0.2 ± 0.1

0.5 ± 0.2

0

T

P = 0.77

P = 0.51

 

P = 0.55

 

P = 0.36

P = 1.0

P = 0.04

 

September 4

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

1.0 ± 0.5

0

0

0.3 ± 0.2

0

0

0.3 ± 0.2

0.3 ± 0.2

0

Pyrethroid

2.8 ± 1.0

0

0

0.7 ± 0.3

0

0

0.2 ± 0.1

0

0

T

P = 0.13

 

 

P = 0.44

 

 

P = 0.42

P = 0.24

 

September 16

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0.1 ± 0.1

0

0

0.9 ± 0.5

0

0

0.2 ± 0.2

0.8 ± 0.3

0.1 ± 0.1

Pyrethroid

0.5 ± 0.3

0

0

0.8 ± 0.5

0

0

0.3 ± 0.2

0

0

T

 P = 0.18

 

 

P = 0.89

 

 

P = 0.50

P = 0.04

P = 0.36

Season long summation

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

7.4 ± 2.6

36.1 ± 2.6

2.3 ± 0.7

2.3 ± 0.8

0.6 ± 0.3

0.4 ± 0.2

1.3 ± 0.5

1.5 ± 0.4

0.1 ± 0.1

Pyrethroid

10.3 ± 2.1

18.5 ± 2.2

1.6 ± 0.6

2.3 ± 0.4

0.6 ± 0.2

0.1 ± 0.1

1.7 ± 0.4

0.8 ± 0.1

0

T

P = 0.41

P <0.01

P = 0.46

P = 1.0

P = 1.0

P = 0.17

P = 0.69

P = 0.17

P = 0.36

 

Whaleyville, MD

Season Total

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0.1 ± 0.1

1.6 ± 0.5

0

0.2 ± 0

0

0

0.6 ± 0.2

2.5 ± 0.6

0.1 ± 0.1

Pyrethroid

0.1 ± 0.1

0.3 ± 0.2

0

0.1 ± 0.1

0

0

0.5 ± 0.1

2.9 ± 0.6

0.1 ± 0.1

T -test

P = 1.0

P = 0.06

 

P = 0.06

 

 

P = 0.86

P = 0.66

P = 1.0

August 21

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0.1 ± 0.1

0.9 ± 0.5

0

0.2

0

0

0.2 ± 0.2

0.1 ± 0.1

0.1 ± 0.1

Pyrethroid

0

0.2 ± 0.1

0

0.1 ± 0.1

0

0

0.3 ± 0.1

0.3 ± 0.3

0

T -test

P = 0.356

P = 0.218

 

P = 0.024

 

 

P = 0.816

P = 0.463

P = 0.356

August 28

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0.1 ± 0.1

1.0 ± 0.1

0

0

0

0

0.2 ± 0

0.1 ± 0.1

0.1 ± 0.1

Pyrethroid

0

0.1 ± 0.1

0

0

0

0

0.3 ± 0.2

0.1 ± 0.1

0.1 ± 0.1

T -test

P = 0.374

P = 0.008

 

 

 

 

P = 0.025

P = 1.0

P = 0.678

September 4

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0

0

0

0

0

0

0.1 ± 0.1

0.1 ± 0.1

0

Pyrethroid

0.1 ± 0.1

0

0

0

0

0

0

0.1 ± 0.1

0

T -test

P = 0.356

 

 

 

 

 

P = 0.134

P = 0.521

 

September 15

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0

0

0

0

0

0

0.1 ± 0.1

0.5 ± 0.1

0

Pyrethroid

0

0

0

0

0

0

0.1 ± 0.1

0.2 ± 0.0

0

T -test

 

 

 

 

 

 

P = 1.0

P = 0.128

 

September 25

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0

0

0

0

0

0

0.1 ± 0.05

1.8 ± 0.4

0

Pyrethroid

0.04 ± 0.04

0

0

0

0

0

0.1 ± 0.05

2.2 ± 0.5

0

T-test

 

 

 

 

 

 

P = 1.0

P = 0.528

 

Seaford, DE

July 31

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0

0.3 ± 0.1

0.2 ± 0.1

0

0

0

0.1 ± 0.1

0

0

Pyrethroid

0

0.1 ± 0.1

0

0

0

0.1 ± 0.1

0.3 ± 0.2

0

0

T - test

 

P = 0.44

P = 0.22

 

 

P = 0.42

P = 0.54

 

 

August 14

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0

0.5 ± 0.3

0

0

0

0

0.8 ± 0

0

0

Pyrethroid

0.1 ± 0.1

0

0

0.1 ± 0.1

0

0

0.1 ± 0.1

0.1 ± 0.1

0

T - test

P = 0.18

P = 0.34

 

P = 0.39

 

 

P <0.01

P = 0.18

 

August 21

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0

4.6 ± 1.2

0

0

0

0

0.6 ± 0.6

0.4 ± 0

0.1 ± 0.1

Pyrethroid

0.2 ± 0.1

0

0

0

0

0

0

0.8 ± 0.2

0

T - test

P = 0.22

P = 0.16

 

 

 

 

P = 0.50

P = 0.24

P = 0.50

August 27

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0

6.2 ± 0.8

0

0

0

0

1.4  ± 0.2

0.5 ± 0.1

0

Pyrethroid

0.1 ± 0.1

0.2 ± 0.1

0

0

0

0

0.3  ± 0.1

0.1 ± 0.1

0

T - test

P = 0.39

P = 0.08

 

 

 

 

P = 0.06

P = 0.07

 

September 4

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0.2

0

0

0

0

0

0.8

0.4

0

Pyrethroid

0.04 ± 0.04

0

0

0

0

0

0.08 ± 0.05

1.0 ± 0.3

0

September 15

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0

0

0

0.2

0

0

0.6

0.2

0

Pyrethroid

0

0

0

0.1 ± 0.1

0

0

0.7  ± 0.3

1.4  ± 0.5

0.04  ± 0.04

September 25

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0

0

0

0.4

0

0

0.4

1.0

0

Pyrethroid

0

0

0

0.1 ± 0.1

0

0

0.6 ± 0.2

1.8 ± 0.7

0

Georgetown, DE

July 14

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

2.5 ± 1.2

0

0

0

0

0

1.3 ± 0.5

0

0

Pyrethroid

0.3 ± 0.3

0

0.5 ± 0.5

0.8 ± 0.3

0

0

0.5 ± 0.5

0

0

T - test

P = 0.15

 

 

P = 0.06

 

 

P = 0.32

 

 

August 3

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0.4 ± 0.2

0.4 ± 0.2

0.4 ± 0.4

0

0.2 ± 0.2

0

0.6 ± 0.2

0

0

Pyrethroid

0

0

0.4 ± 0.4

0

0

0

0

0

0

T - test

P = 0.18

P = 0.18

P = 1.0

 

P = 0.37

 

P = 0.07

 

 

August 14

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0

8.2 ± 1.6

0

0.2 ± 0.2

0

0

0.2 ± 0.2

0.2 ± 0.2

0

Pyrethroid

1.0 ± 0.5

6.0 ± 1.6

0

0.4 ± 0.2

0

0

0

0

0

T - test

P = 0.14

P = 0.36

 

P = 0.55

 

 

P = 0.37

P = 0.37

 

August 21

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0.6 ± 0.2

10.4 ± 1.4

0

0.2 ± 0.2

0

0

0

0.8 ± 0.4

0

Pyrethroid

0.8 ± 0.4

8.4 ± 1.4

0

0

0

0

0

0.2 ± 0.2

0.2 ± 0.2

T - test

P = 0.67

P = 0.34

 

P = 0.37

 

 

 

P = 0.21

P = 0.37

August 27

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0

0

0

0

0

0

0

0

0

Pyrethroid

0.2 ± 0.2

1.4 ± 0.5

0

0

0

0

0

0.4 ± 0.2

0

T - test

P = 0.37

P = 0.05

 

 

 

 

 

P = 0.18

 

September 4

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

0

0

0

0

0

0

0

0

0

Pyrethroid

0

0

0

0

0

0

0

0

0

T - test

 

 

 

 

 

 

 

 

 

September 17

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

1.0 ± 0.4

0

0

0.6 ± 0.4

0

0

0

1.4 ± 0.5

0

Pyrethroid

0

0

0

008 ± 0.4

0

0

0

1.4 ± 0.7

0

T - test

P = 0.09

 

 

 

 

 

 

P = 1.0

 

Total

Trt

BLB

GCW

JB

SB

DSB

BEB

GH

SL

CEW

UTC

4.0 ± 0.8

19.0 ± 2.6

0.4 ± 0.4

1.0 ± 0.5

0.2 ± 0.2

0

1.8 ± 0.6

2.4 ± 0.9

0

Pyrethroid

2.2 ± 0.7

15.8 ± 2.6

0.8 ± 0.5

1.8 ± 0.4

0

0

0.4 ± 0.4

2.0 ± 0.7

0.2 ± 0.2

T - test

P = 0.13

P = 0.41

P = 0.55

P = 0.27

P = 0.37

 

P = 0.09

P = 0.74

P = 0.37

2021

Yield was not significantly impacted by insecticide application at any location. Overall difference between treatment and untreated plots was 0.3 bushels, representing a very slight potential return if the difference is true. Three of the 7 locations had numerically greater yield in the untreated strips. The other four locations had numerically higher yield in the treated strips.

Defoliator insects were generally reduced in the treated strips, especially among green cloverworm and grasshoppers. There were trends at several sites for overall season reduction in bean leaf beetle and stink bug counts, which were unexpected given the length of time after treatment. Counts were generally low for all defoliators and pod feeders. Only at 1 site (Harbeson) did defoliator counts near a level of concern, even though percentage defoliation did not reach a level of concern.  Green cloverworm at this site rapidly declined on their own without insecticide application. Stink bug counts exceeded threshold levels towards the end of the season at Harbeson but were not treated. Unfortunately, yield data was not collected at this site. Spider mites, corn earworm, and soybean looper, pests for which we hypothesized could be flared by in-season pyrethroid use, were present in populations too low to test.

 

2021 Insect Scouting data

Location

Yield treated strips

Yield untreated strips

T-test

Harrington 1

54.7 ± 3.8

54.8 ± 3.2

t = 0.03, df = 3.9, P = 0.978

Milford

73.0 ± 0.5

71.6 ± 3.4

T = -0.41, df = 1.04, P = 0.751

Whaleyville 1

64.9 ± 0.6

64.3 ± 1.2

t = -0.45, df = 3.03, P = 0.680

Whaleyville 2

59.0

59.0 ± 0.5

t = 0, df = 1, P = 1.0

Houston

57.9 ± 1.3

58.2 ± 0.6

T = 0.20, df = 2.73, P = 0.854

Seaford

72.2 ± 0.4

70.4 ± 1.3

T = -1.34, df = 2.38, P = 0.295

Harrington 2

84.4 ± 1.3

83.5 ± 1.4

t = -0.484, df = 3.97, P = 0.654

OVERALL

66.3 ± 2.5

66.0 ± 2.3

t = -0.09, df = 34.5, P = 0.932

Field 1, Harrington

Date

Difference between Treated strips and Untreated Strips (treatment mean; untreated mean)

GCW

GH

JB

BLB

SL

Other Defol.

Total Defol.

DSB

CEW

SB

MPB

Total Preds.

Leaflet

MPB

Leaflet

Thrips

Leaflet

TSSM

Jul 7

-0.4

(0.2, 0.6)

-0.4

(0.1, 0.5)

-

-

-

-0.2

(0.1, 0.3)

-1

-

-

0.1

(0.2, 0.1)

0.7

(1.8, 1.1)

 

0.6

(1.4, 0.8)

-11.3

(18.4, 29.7)

-0.1

(0.3, 0.3)

Jul 12

-0.3

(0.6, 1.0)

-0.3

(0.4, 0.8)

0

-

-

-0.2

(0.1, 0.3)

-0.9

-

-

0.2

(0.2, 0)

1.7

(2.8, 0.9)

 

-0.3

(1.2, 1.4)

4.3

(23.6, 19.3)

-0.5

(0.5, 1.0)

Jul 20

-0.4

(0.6, 1.0)

-0.2

(0.3, 0.5)

-0.1

(0.4, 0.5)

1

(2.6, 1.6)

-

0.2

(0.2, 0)

0.5

 

-

-

0.1

(0.3, 0.3)

0.2

(1.2, 1.0)

 

0.3

(0.4, 0.2)

5.6

(10.8, 5.2)

2.8

(3.3, 0.4)

Jul 26

0.3

(2.5, 2.3)

-0.3

(0, 0.3)

-0.4

(0.3, 0.8)

-0.2

(1.7, 1.8)

-

-

0.6

0

(0.3, 0.3)

-

-0.2

(0.1, 0.3)

-0.3

(2.8, 3.2)

 

0.8

(1.3, 2.1)

1.3

(16.5, 15.3)

-1.4

(16.5, 15.3)

Aug 2

-1.6

(5.5, 7.1)

-1.1

(0.3, 1.3)

-0.8

(0.2, 1.0)

-0.4

(0.3, 0.8)

-

-0.2

(0.1, 0.3)

-0.2

-0.3

-

-0.3

(0.2, 0.4)

-0.1

(0.1, 0.2)

 

 

 

 

Aug 9

-1

(5.4, 6.4)

-1.1

(0.3, 1.4)

-0.3

(0.3, 0.7)

-0.8

(0.4, 1.3)

-

0

(0.2, 0.2)

-3.3

0

(0.2, 0.2)

-

-0.3

(0.2, 0.5)

-0.4

(0.2, 0.6)

 

 

 

 

Aug 19

-0.7

(0.2, 0.8)

0.3

(1.1, 0.8)

0.1

(0.2, 0.1)

-0.6

(0.3, 0.8)

-

-

-0.8

 

-

-

0.1

(0.1, 0)

-0.3

(0, 0.3)

 

 

 

 

Aug 25

-1.2

(1.0, 2.2)

-0.2

(0.5, 0.7)

-

0.4

(0.5, 0.1)

-

0.1

(0.3, 0.2)

-0.6

-0.1

(0, 0.1)

-

-0.1

(0, 0.1)

0.3

(0.3, 0)

 

 

 

 

Sept 1

-0.5

(1.3, 1.8)

0.2

(0.9, 0.8)

-

-0.2

(0.8, 1.0)

-

0.1

(0.3, 0.2)

-0.4

-0.2

(0, 0.2)

-

0.2

(0.3, 0.1)

-0.3

(0.4, 0.7)

 

 

 

 

Sept 9

0.3

(1.2, 0.9)

-0.1

(0.7, 0.8)

0

(0.1, 0.1)

0.1

(1.3, 1.3)

-

0.1

(0.3, 0.2)

0.1

-

-

-0.2

(0.3, 0.4)

-0.3

(0.1, 0.3)

 

 

 

 

Sept 15

0

(0.6, 0.6)

0

(0.6, 0.6)

-

-0.3

(0.8, 1.1)

-

0

(0.2, 0.2)

-0.3

0

(0.1, 0.1)

-0.2

(0, 0.2)

-0.3

(0.3, 0.6)

-

 

 

 

 

Sept 22

0.2

(1.0, 0.8)

-0.3

(0.3, 0.6)

-

-0.2

(0.4, 0.6)

-

0.2

(0.3, 0.2)

-0.2

-

-

0.2

(0.7, 0.5)

-

 

 

 

 

 

Season Total

Trt

JB

BLB

SB

DSB

GCW

GH

CEW

Other Defol

SL

Total Pred

MPB

LFL MPB

LFL Mites

LFL Thrips

UTC

3.3 ± 0.8

10.3± 1.8

3.4± 0.7

1.1± 0.2

24.8± 1.4

8.9± 1.3

0.2± 0.2

1.8± 0.2

0

11.5± 0.3

8.1± 1.0

4.5± 0.4

4.8± 2.5

69.3± 6.1

Pyreth.

1.75 ± 0.3

9.1± 0.2

2.8± 0.3

0.6± 0.2

19.3± 1.8

5.4± 0.5

0

1.8± 0.6

0

13.6± 1.6

9.3± 0.4

4.3± 2.0

5.8± 2.4

69.3± 8.7

T

P=0.2

 

df=2.5

P=0.6

 

df=2.0

P=0.5

 

df=2.7

P=0.2

 

df=4

P=0.1

 

df=3.8

P=0.1

 

df=2.7

P=0.4

 

df=2

P=1.0

 

df=2.6

 

P=0.3

 

df=2.1

P=0.3

 

df=2.8

P=0.9

 

df=2.2

P=0.8

 

df=4.0

P=1.0

 

df=3.6

 

 

 

 

Field 2 Milford

Date

Difference between Treated strips and Untreated Strips (treatment mean; untreated mean)

 

GCW

GH

JB

BLB

SL

Other Defol.

Total Defol.

DSB

CEW

SB

MPB

Total Preds.

Leaflet

MPB

Leaflet

Thrips

Leaflet

TSSM

July 29

-

-

-

-

-

-

-

-

0.1

(0.1, 0)

-

-0.1

(0.3, 0.3)

 

-

0.6

(1.6, 1.0)

0.4

(0.4, 0)

Aug 2

-0.2

(0, 0.2)

-0.2

(0.1, 0.3)

-0.3

(0, 0.3)

-

-

-0.3

(0.1, 0.3)

-0.8

-

-

-0.1

(0, 0.1)

-0.3

(0.6, 0.8)

 

 

 

 

Aug 9

-

-0.5

(0, 0.5)

-0.1

(0, 0.1)

-

-

-0.4

(0.2, 0.6)

-1

-

-

0.3

(0.3, 0)

0.3

(0.4, 0.1)

 

 

 

 

Aug 19

-0.3

(0.1, 0.3)

0.1

(0.3, 0.3)

0

(0.1, 0.1)

-0.1

(0.2, 0.3)

-

0.2

(0.5, 0.3)

-0.1

-

-

0

(0.2, 0.2)

-0.3

(0.2, 0.5)

 

 

 

 

Aug 25

0.1

(0.1, 0)

-

0.2

(0.2, 0)

-

0.1

(0.2, 0.1)

-0.3

(0, 0.3)

0.1

-

-

-0.1

(0, 0.1)

-0.8

(1.2, 2.0)

 

 

 

 

Sept 1

0.1

(0.2, 0.1)

0

(0.1, 0.1)

-0.1

(0, 0.1)

0.1

(0.2, 0.1)

-0.2

(0, 0.2)

0.3

(0.4, 0.1)

0.3

-

-0.1

(0, 0.1)

0

(0.2, 0.2)

0.2

(0.8, 0.7)

 

 

 

 

Sept 9

0.2

(0.2, 0.1)

-0.2

(0.3, 0.4)

-

-0.3

(0.5, 0.8)

-

-0.2

(0.3, 0.4)

-0.8

-

0.1

(0.1, 0)

-0.3

(0.1, 0.4)

-0.3

(0.5, 0.8)

 

 

 

 

Sept 15

0

(0.3, 0.3)

-0.3

(0.4, 0.7)

-

-0.3

(0.2, 0.4)

-

0.3

(0.3, 0.1)

-0.3

-

-

-0.2

(0.1, 0.3)

-0.3

(0.8, 1.1)

 

 

 

 

Sept 22

0.1

(0.3, 0.3)

-0.1

(0.3, 0.4)

-

0

(0.2, 0.2)

-

-0.1

(0.3, 0.4)

-0.1

-

-0.1

(0, 0.1)

0

(0.1, 0.1)

-0.3

(0.8, 1.0)

 

 

 

 

Sept 30

0.1

(0.2, 0.1)

-0.3

(0.3, 0.6)

-

0.2

(0.3, 0.2)

-

0.2

(0.5, 0.3)

0.1

-

-

0

(0.1, 0.1)

-0.5

(0.5, 1.0)

 

 

 

 

Oct 6

-0.2

(0, 0.2)

0.2

(0.3, 0.1)

-

-0.1

(0.1, 0.2)

-

0

(0.2, 0.2)

-0.1

-

-

-0.1

(0.2, 0.3)

-

 

 

 

 

 

 

 

 

 

Field 2 Milford Season Total

Trt

JB

BLB

SB

DSB

GCW

GH

CEW

Other Defol

SL

Total Pred

MPB

LFL MPB

LFL Mites

LFL Thrips

UTC

0.5 ± 0.3

2.0± 0.1

1.6± 0.1

0

1.7± 0.5

3.3± 0.8

0.2± 0.2

2.9± 1.2

0.3

9.3± 3.5

8.3± 3.2

0

0

1.0± 1.0

Pyreth.

0.3 ± 0.1

1.6± 0.2

1.1± 0.1

0

1.3± 0.5

2.0± 0.6

0.2± 0.1

2.7± 0.5

0.2± 0.1

7.1± 2.1

5.9± 1.8

0

0.4± 0.4

1.6± 0.5

T

P=0.5

 

df=2.9

P=0.2

 

df=3.4

P=0.01

 

df=4

 

P=0.6

 

df=4.0

P=0.3

 

df=3.9

P=1.0

 

df=2.9

P=0.9

 

df=2.7

P=0.4

 

df=2

P=0.6

 

df=3.3

P=0.6

 

df=3.2

 

P=0.4

 

df=2

P=0.6

 

df=3.0

 

 

 

 

Field 3, Whaleyville, MD

Date

Difference between Treated strips and Untreated Strips (treatment mean; untreated mean)

 

GCW

GH

JB

BLB

SL

Other Defol.

Total Defol.

DSB

CEW

SB

MPB

Total Preds.

Leaflet

MPB

Leaflet

Thrips

Leaflet

TSSM

July 30

-0.9

(0.3, 1.1)

-0.1

(0.1, 0.3)

-0.1

(0.2, 0.3

-0.3

(0.1, 0.4)

-

-0.5

(0.2, 0.7)

-6

-

-0.2

(0, 0.2)

0.2

(0.2, 0)

-2.5

(0.4, 2.9)

 

-0.3

(0.1, 0.4)

1.1

(34.3, 33.2)

-

Aug 5

-0.1

(0.2, 0.3)

-0.2

(0.2, 0.4)

-0.2

(0.4, 0.6)

0

(0.1, 0.1)

-

-0.4

(0.2, 0.6)

-1.5

-

-

0.1

(0.1, 0)

0.3

(0.9, 0.6)

 

 

 

 

Aug 11

-0.9

(0.1, 0.9)

0.1

(0.1, 0)

0.4

(0.9, 0.5)

-0.3

(0, 0.3)

-

-0.1

(0.4, 0.5)

0.3

-

-

-0.1

(0, 0.1)

1.7

(5.1, 3.4)

 

 

 

 

Aug 18

-3.0

(2.7, 5.7)

0

(0.2, 0.2)

-0.4

(0.3, 0.7)

0.2

(0.4, 0.2)

0

(0.1, 0.1)

-0.1

(0.2, 0.3)

-10.1

-

-

0.1

(0.1, 0)

-2.9

(7.6, 10.5)

 

 

 

 

Aug 27

-1.1

(1.3, 2.3)

0

(0.1, 0.1)

0.1

(0.3, 0.1)

0.5

(1.0, 0.4)

0

(0.1, 0.1)

-0.1

(0.2, 0.3)

0.1

-

-

-0.1

(0.2, 0.3)

1.4

(4.5, 3.1)

 

 

 

 

Sept 2

-1.3

(1.1, 2.4)

0.1

(0.2, 0.1)

-0.2

(0, 0.2)

0.8

(0.9, 0.1)

-

0.1

(0.1, 0)

-2.5

-

-

0.1

(0.1, 0)

-0.3

(2.9, 3.2)

 

 

 

 

Sept 10

-0.4

(0.6, 1.0)

0.3

(0.4, 0.1)

0.1

(0.1, 0)

0.3

(1.4, 1.1)

-

-0.2

(0, 0.2)

-1.4

-

-

-0.3

(0, 0.3)

-1.1

(3.1, 4.5)

 

 

 

 

Sept 17

-0.8

(0.7, 1.5)

0.3

(0.3, 0)

-

-0.9

(1.2, 2.1)

-

0.2

(0.3, 0.1)

-2.1

-

0

(0.1, 0.1)

-0.1

(0.2, 0.3)

-0.9

(2.0, 2.9)

 

 

 

 

Sept 24

0.1

(1.2, 1.1)

-0.1

(0, 0.1)

-

-0.5

(2.0, 2.5)

-

0

(0.1, 0.1)

-0.5

-

-

0.1

(0.3, 0.3)

0.1

(1.3, 1.2)

 

 

 

 

Oct 1

-0.6

(0.7, 1.3)

0.3

(0.5, 0.3)

-

-0.8

(1.3, 2.1)

-

-

-0.7

-

-0.1

(0, 0.1)

-0.1

(0.3, 0.3)

0.7

(1.1, 0.4)

 

 

 

 

Oct 8

-0.3

(0.3, 0.5)

 

0.3

(0.5, 0.2)

-

-0.6

(0.7, 1.3)

-

-

-0.3

-

-

0.1

(0.4, 0.3)

-0.1

(0.5, 0.6)

 

 

 

 

 Season Total

Trt

JB

BLB

SB

DSB

GCW

GH

CEW

Other Defol

SL

Total Pred

MPB

LFL MPB

LFL Mites

LFL Thrips

UTC

2.5 ± 0.8

10.8± 1.1

1.9± 0.4

0

18.3± 4.1

1.7± 0.5

0.3± 0.2

2.9± 0.2

0.2± 0.2

35.6± 1.9

33.1± 2.4

0.4± 0.2

0

33.2± 6.5

Pyreth.

2.2 ± 0.5

9.3± 1.4

1.7± 0.5

0

9.1± 3.2

2.7± 0.3

0.1± 0.1

1.8± 0.2

0.2± 0.1

31.7± 0.5

29.4± 0.9

0.1± 0.1

0

34.3± 8.5

T

P=0.8

 

df=6.5

P=0.4

 

df=7.7

P=0.8

 

df=7.7

 

P=0.1

 

df=7.6

P=0.1

 

df=6.6

P=0.2

 

df=5.0

P=0.01

 

df=7.1

P=1.0

 

df=5.3

P=0.1

 

df=4.5

P=0.2

 

df=5.0

P=0.1

 

df=5.3

 

P=0.9

 

df=7.5

 

 

 

 

 

Field 4 Houston

Date

Difference between Treated strips and Untreated Strips (treatment mean; untreated mean)

 

GCW

GH

JB

BLB

SL

Other Defol.

Total Defol.

DSB

CEW

SB

MPB

Total Preds.

Leaflet

MPB

Leaflet

Thrips

Leaflet

TSSM

June 9

-

-0.3

(0.2, 0.4)

-

-0.7

(0.1, 0.8)

-

-

-0.9

-

-

-

-

 

-

-

-

June 14

-

-0.3

(0.2, 0.4)

-

-0.3

(0.5, 0.8)

-

-

-0.6

-

-

-

-

 

0.3

(0.4, 0.1)

1.4

(19.7, 18.3)

-

June 21

0

(0.3, 0.3)

0.4

(0.6, 0.2)

-

-0.1

(0.5, 0.6)

-

-

0.3

-

-

-

-

 

0.1

(3.1, 3.0)

9.8

(23.0, 13.3)

-

June 29

0.3

(0.8, 0.5)

0.3

(0.4, 0.2)

0.1

(0.3, 0.2)

0.1

(0.1, 0)

-

0.1

(0.1, 0)

0.9

-

-

-0.2

(0.1, 0.3)

0.9

(2.9, 3.8)

 

0

(0.6, 0.6)

-19.1

(9.2, 28.3)

-0.2

(0, 0.2)

Jul 8

-0.6

(0.3, 0.9)

0

(0.2, 0.2)

-0.6

(0.4, 0.8)

0.1

(0.1, 0)

-

-0.1

(0.1, 0.2)

-1.4

-

-

0.2

(0.3, 0.1)

0.3

(1.6, 1.3)

 

-0.5

(0.3, 0.8)

-9.9

(9.3, 19.2)

1.3

(1.3, 0.1)

Jul 12

-0.3

(0.7, 0.9)

-0.3

(0.2, 0.4)

0.3

(1.4, 1.1)

0.2

(0.5, 0.3)

-

-0.5

(0.2, 0.7)

-0.9

-

-

-0.2

(0.4, 0.6)

-1.3

(2.3, 3.6)

 

0.4

(0.6, 0.2)

2.8

(12.7, 9.9)

0.3

(0.6, 0.3)

Jul 23

-0.1

(0.2, 0.3)

0

(0.3, 0.3)

-0.8

(2.0, 1.3)

-0.8

(2.8, 2.0)

-

-

-1.3

0.7

(1.2, 0.6)

-

-0.1

(0, 0.1)

-0.9

(0, 0.9)

 

-0.1

(0, 0.1)

1.9

(3.7, 1.8)

-0.5

(0.2, 0.7)

Jul 27

0.2

(1.4, 1.3)

-0.1

(0.2, 0.3)

0.3

(1.0, 0.8)

0.3

(5.8, 5.5)

-

-

0.7

0.1

(0.6, 0.5)

-

-0.2

(0.1, 0.3)

1.5

(2.7, 1.2)

 

0.2

(0.8, 0.7)

-0.5

(5.4, 5.9)

-0.2

(0, 0.2)

Aug 4

0

(1.8, 1.8)

0.5

(0.8, 0.3)

0

(0.7, 0.7)

0.5

(6.3, 5.8)

-

-0.2

(0.2, 0.4)

0.7

0.3

(0.4, 0.2)

-

-0.3

(0.4, 0.7)

0.9

(1.8, 0.9)

 

 

 

 

Aug 10

0.1

(1.3, 1.3)

-0.3

(0.4, 0.7)

0.1

(0.7, 0.6)

-3.3

(5.3, 9.3)

-

0.2

(0.5, 0.3)

-3.6

0.1

(0.3, 0.3)

-

-0.3

(0.9, 1.3)

0.9

(1.8, 0.9)

 

 

 

 

Aug 18

-0.3

(2.2, 2.5)

0.1

(0.7, 0.6)

0.4

(0.6, 0.2)

-4.1

(5.3, 9.3)

0.1

(0.1, 0)

0.3

(0.4, 0.1)

-3.6

-0.1

(0.5, 0.6)

-0.1

(0, 0.1)

-0.4

(0.9, 1.3)

-0.2

(0.7, 0.9)

 

 

 

 

Aug 31

0.2

(2.5, 2.3)

0.1

(0.9, 0.8)

-0.1

(0.3, 0.4)

-1.5

(4.4, 5.9)

-

0.3

(0.4, 0.1)

-1

-0.1

(0.5, 0.6)

0.1

(0.1, 0)

0.2

(1.0, 0.8)

0

(1.3, 1.3)

 

 

 

 

Sept 7

-1.3

(1.9, 3.3)

0.3

(0.3, 0.1)

-0.3

(0.1, 0.4)

-0.5

(3.2, 3.7)

-

0.1

(0.1, 0)

-1.8

-0.2

(0.2, 0.3)

-

-0.6

(0.6, 1.2)

-0.6

(1.4, 2.0)

 

 

 

 

Sept 16

0.8

(2.4, 1.7)

0.3

(0.6, 0.3)

-0.1

(0.1, 0.2)

-1.3

(1.7, 2.9)

-

0.3

(0.3, 0.1)

0

-0.3

(0.3, 0.6)

0.1

(0.1, 0)

-0.2

(1.0, 1.2)

-0.9

(1.6, 2.5)

 

 

 

 

Sept 21

-0.5

(1.2, 1.7)

-0.6

(0.3, 0.8)

-

-0.7

(1.8, 2.5)

0.1

(0.1, 0)

0.1

(0.1, 0)

-1.7

-0.4

(0.4, 0.8)

-

-0.6

(0.6, 1.2)

-0.9

(1.0, 1.9)

 

 

 

 

 

Season Total

Trt

JB

BLB

SB

DSB

GCW

GH

CEW

Other Defol

SL

Total Pred

MPB

LFL MPB

LFL Mites

LFL Thrips

UTC

6.5 ± 1.9

47.2± 3.1

8.3± 0.7

4.2± 0.5

18.3± 0.9

5.9± 0.7

0.1± 0.1

1.8± 0.5

0

24.2± 0.7

20.4± 1.0

2.4± 0.4

1.3± 0.4

83.3± 1.8

Pyreth.

7.6 ± 0.8

36.9± 3.5

5.8± 0.8

4.2± 0.6

16.8± 3.0

5.7± 0.4

0.2± 0.2

2.2± 0.5

0.1± 0.1

22.4± 1.5

18.0± 1.3

2.7± 0.8

2.1± 0.7

59.9± 1.4

T

P=0.6

 

df=2.7

P=0.1

 

df=4.0

P=0.1

 

df=4.0

P=1.0

 

df=4.0

P=0.7

 

df=2.4

P=0.8

 

df=2.9

P=0.7

 

df=2.9

P=0.6

 

df=4

P=0.4

 

df=2

P=0.4

 

df=2.7

P=0.2

 

df=3.7

P=0.8

 

df=2.9

P=0.4

 

df=3.3

P=>0.001

 

df=3.8

 

 

 

 

 

 

 

 

 

Field 5 Harbeson

Date

Difference between Treated strips and Untreated Strips (treatment mean; untreated mean)

 

GCW

GH

JB

BLB

SL

Other Defol.

Total Defol.

DSB

CEW

SB

MPB

Total Preds.

Leaflet

MPB

Leaflet

Thrips

Leaflet

TSSM

Jul 30

-3

(2.3, 5.3)

-0.1

(0, 0.1)

-0.7

(0.1, 0.8)

0.4

(1.4, 1.0)

-

-1.2

(0.9, 2.1)

-4.6

-0.6

(0.2, 0.8)

-0.1

(0, 0.1)

-0.1

(0, 0.1)

0.6

(1.3, 0.9)

 

0.9

(1.0, 0.1)

-3.7

(22.6, 26.2)

-0.1

(0, 0.1)

Aug 5

-9.7

(2.8, 12.4)

0

(0.1, 0.1)

-0.3

(0, 0.3)

0.2

(1.4, 1.3)

0

(0.1, 0.1)

-3.3

(1.4, 4.8)

-13.1

-0.1

(0, 0.1)

-

0.1

(0.1, 0)

0.8

(2.7, 1.9)

 

 

 

 

Aug 13

-6.2

(3.4, 9.7)

 

0.1

(0.2, 0.1)

0

(0.1, 0.1)

0.1

(1.4, 1.3)

-

-1.6

(2.1, 3.7)

-7.6

0.1

(0.1, 0)

-

-0.3

(0.1, 0.4)

0.4

(2.9, 2.4)

 

 

 

 

Aug 18

-1.3

(5.6, 6.9)

0.5

(0.7, 0.2)

-0.1

(0, 0.1)

0.4

(6.2, 5.8)

0.1

(0.1, 0)

0

(0.3, 0.3)

-0.4

-

-

0

(0.3, 0.3)

0.8

(1.2, 0.4)

 

 

 

 

Aug 23

-0.1

(3.6, 3.7)

0.6

(1.2, 0.6)

-

-0.1

(5.0, 5.1)

0

(0.1, 0.1)

0

(0.1, 0.1)

0.4

-

-

-0.3

(0.1, 0.4)

0.1

(0.3, 0.2)

 

 

 

 

Sept 2

1.2

(3.3, 2.1)

0.1

(0.9, 0.8)

-

-3.0

(3.8, 6.8)

0.1

(0.1, 0)

0.1

(0.1, 0)

-1.4

-

-

-0.6

(0.1, 0.7)

-0.3

(0.4, 0.8)

 

 

 

 

Spet 10

-0.2

(1.1, 1.3)

0.4

(0.7, 0.3)

-

-1.8

(8.6, 10.3)

-

0.1

(0.2, 0.1)

-1.6

-

-

0

(2.3, 2.3)

-

 

 

 

 

Sept 17

-0.2

(0.2, 0.4)

0.1

(0.3, 0.2)

-

2.6

(11.0, 8.4)

0.2

(0.2, 0)

-0.4

(0, 0.4)

2.2

-

-

1.7

(3.8, 2.1)

-

 

 

 

 

Sept 24

0.2

(0.2, 0)

0

(0.2, 0.2)

-

-0.7

(8.6, 9.2)

-0.1

(0.1, 0.2)

-0.3

(0.2, 0.6)

-0.9

-

-

-2.6

(1.7, 4.3)

0.1

(0.2, 0.1)

 

 

 

 

Oct 1

0.2

(0.4, 0.2)

-0.1

(0.3, 0.4)

-

-1.1

(3.0, 4.1)

-0.1

(0, 0.1)

0.1

(0.1, 0)

-1

-

-

0.1

(1.3, 1.2)

-

 

 

 

 

Oct 8

0.3

(0.6, 0.2)

-0.4

(0.2, 0.6)

-

-0.3

(1.6, 1.9)

-

0.3

(0.3, 0)

0

-

0.1

(0.1, 0)

-0.3

(1.0, 1.3)

-

 

 

 

 

 

 

Season Total

Trt

JB

BLB

SB

DSB

GCW

GH

CEW

Other Defol

SL

Total Pred

MPB

LFL MPB

LFL Mites

LFL Thrips

UTC

1.3 ± 0.4

55.4± 5.7

13.2± 2.1

0.9± 0.5

42.3± 2.7

3.7± 0.9

0.1± 0.1

12.1± 1.8

0.6± 0.3

19.8± 1.5

6.7± 0.9

0.1± 0.1

0.1± 0.1

26.2± 3.0

Pyreth.

0.2 ± 0.1

52.2± 6.4

10.9± 1.4

0.3± 0.2

23.6± 2.5

4.9± 0.9

0.1± 0.1

5.9± 1.3

0.8± 0.2

18.3± 1.6

9.1± 1.0

1.0± 0.4

0

22.6± 3.9

T

P= 0.1 df= 9.8

P=0.7

 

df=15.8

P=0.4

 

df=14.2

P=0.3

 

df=12.0

P=<.0001

 

df=15.9

P=0.4

 

df=16.0

P=1.0

 

df=16

P=0.02

 

df=14.7

P=0.6

 

df=13.8

P=0.5

 

df=15.8

P=0.1

 

df=15.7

P=0.1

 

df=9.0

P=0.3

 

df=8

P=0.5

 

df=15.1

 

Field 6 Seaford

Date

Difference between Treated strips and Untreated Strips (treatment mean; untreated mean)

 

GCW

GH

JB

BLB

SL

Other Defol.

Total Defol.

DSB

CEW

SB

MPB

Total Preds.

Leaflet

MPB

Leaflet

Thrips

Leaflet

TSSM

June 21

-0.5

(0.3, 0.8)

-

-

-0.3

(0.3, 0.5)

-

-

-0.8

-

-

-0.2

(0, 0.2)

-

 

0.1

(0.3, 0.2)

-9.6

(14.4, 24.0)

-

June 28

-0.6

(0.3, 0.9)

0.2

(0.2, 0)

-0.1

(0.1, 0.2)

-0.3

(0.1, 0.4)

-

0.2

(0.2, 0)

-0.7

-

-

-

1.5

(4.5, 3.0)

 

0.3

(0.5, 0.2)

10.3

(43.3, 32.9)

0

(0.3, 0.3)

July 7

-0.3

(0, 0.3)

0.1

(0.1, 0)

1.3

(1.8, 0.5)

-

-

-0.1

(0.1, 0.2)

1.0

-

-

0

(0.2, 0.2)

-1.0

(2.8, 3.8)

 

0.1

(2.1, 2.0)

13.3

(41.1, 27.8)

0.8

(1.9, 1.1)

July 13

-0.1

(0, 0.1)

-

0.5

(1.6, 1.1)

0

(0.8, 0.8)

-

-

0.5

-

-

-0.3

(0, 0.3)

1.7

(4.3, 2.7)

 

0.1

(1.1, 1.0)

-13.2

(15.3, 28.5)

0.8

(1.5, 0.7)

July 23

-0.1

(0.2, 0.3)

0.1

(0.1, 0)

-0.3

(0.8, 1.1)

-1.5

(0.3, 1.8)

-0.1

(0, 0.1)

-

-1.8

-

-

0.1

(0, 0.1)

-

 

0.4

(0.4, 0)

-2.3

(1.9, 4.2)

-2

(2.1, 4.1)

July 28

-0.2

(0, 0.2)

-0.1

(0, 0.1)

-0.6

(0.5, 1.1)

0.1

(0.3, 0.2)

-

-

-0.7

-

-

-0.1

(0, 0.1)

-0.2

(1.1, 1.3)

 

-0.1

(0.4, 0.5)

-2

(5.3, 7.3)

0.1

(0.2, 0.1)

Aug 3

-0.2

(0.2, 0.3)

0.2

(0.3, 0.1)

0.8

(0.8, 0.1)

-

-

-

0.8

-

-

0.2

(0.2, 0)

2.6

(9.4, 6.9)

 

 

 

 

Aug 12

-0.1

(0.3, 0.4)

-0.3

(0.1, 0.4)

-0.2

(1.0, 1.1)

-0.3

(0.4, 0.8)

-

-

-0.9

-

-

-0.1

(0.3, 0.4)

0.7

(10.2, 9.5)

 

 

 

 

Aug 19

0.2

(0.2, 0)

-

0.3

(1.0, 0.8)

0

(0.2, 0.2)

-

-

0.4

 

-

-

0

(0.1, 0.1)

-0.8

(1.3, 2.2)

 

 

 

 

Aug 31

-0.4

(0.4, 0.8)

-0.3

(0.2, 0.4)

-0.1

(0.8, 0.9)

-0.4

(0.4, 0.8)

-

0.1

(0.3, 0.2)

-1.1

0

(0.1, 0.1)

-

-0.1

(0.2, 0.3)

0.3

(1.3, 1.7)

 

 

 

 

Sept 7

-0.7

(0.4, 1.1)

0.1

(0.4, 0.3)

-1.0

(0.3, 1.3)

-1.3

(1.3, 2.6)

-

-0.2

(0, 0.2)

-3.1

-0.1

(0, 0.1)

-

-0.2

(0.3, 0.5)

0.1

(1.3, 1.2)

 

 

 

 

Sept 16

-0.2

(0.9, 1.1)

-0.2

(0.3, 0.4)

-0.2

(0.2, 0.4)

-0.5

(0.8, 1.3)

0.1

(0.1, 0)

-0.2

(0.1, 0.3)

-1.3

-

-

-0.1

(0.3, 0.2)

-0.7

(0.3, 0.9)

 

 

 

 

Sept 21

-0.2

(0.8, 0.9)

-0.5

(0.2, 0.7)

-0.3

(0.2, 0.5)

-0.5

(0.5, 1.0)

-

0.1

(0, 0.1)

-1.4

-0.1

(0, 0.1)

0.1

(0.1, 0)

-0.2

(0.3, 0.5)

-1.0

(0.3, 1.3)

 

 

 

 

 

Season Total

Trt

JB

BLB

SB

DSB

GCW

GH

CEW

Other Defol

SL

Total Pred

MPB

LFL MPB

LFL Mites

LFL Thrips

UTC

9.1 ± 1.5

10.2± 2.0

2.8± 0.5

0.3± 0.1

7.2± 0.9

2.4± 0.3

0

0.9± 0.3

0.1± 0.1

35.6± 0.9

34.3± 1.3

3.8± 0.2

6.3± 0.4

124.6± 10.8

Pyreth.

9.1 ± 2.0

5.3± 0.2

1.8± 0.3

0.1± 0.1

3.9± 1.0

1.7± 0.6

0.1± 0.1

0.7± 0.4

0.1± 0.1

38.4± 2.0

36.8± 1.9

4.8± 0.7

6.0± 2.8

121.3± 25.8

T

P=1.0

 

df=3.6

P=0.1

 

df=2.1

P=0.2

 

df=2.9

P=0.4

 

df=3.2

P=0.1

 

df=4.0

P=0.3

 

df=2.9

P=0.4

 

df=2

P=0.8

 

df=3.6

P=1.0

 

df=4

P=0.3

 

df=2.9

P=0.3

 

df=3.5

P=0.3

 

df=2.2

P=0.9

 

df=2.1

P=0.9

 

df=2.7

 

 

 

 

Field 7 Harrington

Date

Difference between Treated strips and Untreated Strips (treatment mean; untreated mean)

 

GCW

GH

JB

BLB

SL

Other Defol.

Total Defol.

DSB

CEW

SB

MPB

Total Preds.

Leaflet

MPB

Leaflet

Thrips

Leaflet

TSSM

July 16

-0.1

(0, 0.1)

-

-0.2

(0, 0.2)

-

-

-0.2

(0, 0.2)

-0.4

-

-0.1

(0, 0.1)

-

-0.5

(0.3, 0.8)

 

0.2

(0.4, 0.3)

-3.3

(10.1, 13.3)

0.1

(0.2, 0.1)

July 20

-0.3

(0, 0.3)

-

-0.3

(0, 0.3)

0.1

(0.1, 0)

-

-

-0.5

-0.1

(0, 0.1)

-

-0.1

(0, 0.1)

-0.9

(1.9, 2.8)

 

-0.1

(0.1, 0.2)

1.7

(8.1, 6.4)

-0.1

(0, 0.1)

July 26

-0.8

(0.1, 0.9)

-0.2

(0, 0.2)

-0.3

(0.4, 0.7)

0

(0.3, 0.3)

-

-

-1.3

0.2

(0.2, 0)

-

-0.3

(0, 0.3)

1.0

(3.3, 2.3)

 

-0.6

(1.5, 2.1)

6.8

(16.1, 9.3)

-0.1

(0, 0.1)

Aug 2

-1.5

(0.8, 2.3)

-0.1

(0.1, 0.2)

0

(0.2, 0.2)

0

(0.1, 0.1)

-

-0.2

(0.6, 0.8)

-1.8

-0.1

(0, 0.1)

-

0

(0.3, 0.3)

0.4

(0.9, 0.5)

 

 

 

 

Aug 9

0.3

(1.3, 1.0)

-0.1

(0.2, 0.3)

0

(0.3, 0.3)

-0.2

(0.1, 0.3)

-

-0.2

(0.1, 0.3)

-0.2

-0.1

(0, 0.1)

-

0

(0.3, 0.3)

0

(0.4, 0.4)

 

 

 

 

Aug 19

-

-0.1

(0, 0.1)

-

0.1

(0.1, 0)

-

0.1

(0.1, 0)

-0.1

-

-

-

-0.7

(2.8, 3.5)

 

 

 

 

Aug 25

-

-

-

0.1

(0.1, 0)

-

0.1

(0.1, 0)

0.2

-

-

-

2.4

(12.2, 9.8)

 

 

 

 

Sept 1

-0.3

(0.2, 0.4)

0.1

(0.2, 0.1)

0

(0.2, 0.2)

0

(0.2, 0.2)

-

-

-0.2

-

-

0

(0.1, 0.1)

-1.1

(8.5, 9.6)

 

 

 

 

Sept 9

-0.3

(0.1, 0.4)

-0.1

(0.2, 0.3)

-0.1

(0, 0.1)

0.1

(0.4, 0.3)

-

0

(0.2, 0.2)

-0.4

-

0.1

(0.1, 0)

0.2

(0.3, 0.1)

-1.1

(8.3, 9.4)

 

 

 

 

Sept 15

-0.3

(0.6, 0.8)

-0.1

(0.4, 0.5)

-

-0.5

(0.5, 1.0)

-0.1

(0, 0.1)

0.3

(0.5, 0.2)

-0.6

0

(0.1, 0.1)

0.1

(0.1, 0)

-0.3

(0, 0.3)

-1.8

(3.8, 5.6)

 

 

 

 

Sept 22

0

(0.6, 0.6)

-0.3

(0.4, 0.8)

-

-0.4

(0.4, 0.8)

-

-

-0.7

-

-

-0.1

(0.1, 0.2)

0.1

(1.4, 1.5)

 

 

 

 

Sept 30

-0.1

(0.3, 0.4)

0

(0.5, 0.5)

-

-0.3

(0.2, 0.4)

-0.1

(0, 0.1)

-

-0.4

-

-0.1

(0, 0.1)

-0.3

(0.4, 0.7)

-0.1

(0.6, 0.7)

 

 

 

 

Oct 6

0.2

(0.4, 0.2)

-0.3

(0.3, 0.7)

-

-0.2

(0.4, 0.6)

-

-0.1

(0.2, 0.3)

-0.4

-

0

(0.1, 0.1)

-0.2

(0.1, 0.3)

-0.2

(0.7, 0.8)

 

 

 

 

Season Total

Trt

JB

BLB

SB

DSB

GCW

GH

CEW

Other Defol

SL

Total Pred

MPB

LFL MPB

LFL Mites

LFL Thrips

UTC

1.7 ± 0.3

3.9± 0.7

2.5± 0.4

0.3± 0.1

7.3± 1.2

3.4± 0.3

0.2± 0.1

1.9± 0.2

0

49.6± 3.2

47.5± 3.0

2.5± 1.0

0.3

29.0± 2.6

Pyreth.

1.0 ± 0.1

2.7± 0.1

1.4± 0.2

0.3± 0.1

4.3± 1.0

2.3± 0.5

0.3± 0.1

1.6± 0.4

0.2± 0.2

47.3± 5.2

45.3± 5.4

2.0± 0.7

0.2± 0.1

34.3± 2.0

T

P=0.1

 

df=4.5

P=0.2

 

df=2.1

P=0.1

 

df=3.2

P=0.6

 

df=3.2

P=0.1

 

df=3.9

P=0.1

 

df=3.2

P=0.6

 

df=3.2

P=0.5

 

df=2.6

P=0.4

 

df=2

P=0.7

 

df=3.3

P=0.7

 

df=3.1

P=0.7

 

df=3.4

P=0.4

 

df=2

P=0.2

 

df=3.8

Discussion

Defoliating insects were generally negatively impacted by pyrethroid application, sometimes for a surprisingly long period of time. However, defoliation thresholds are very conservative, and even at the 2020 Harbeson site that was treated for defoliators, yield was not affected. It is possible that had the field not been treated by the cooperator that there may have been some yield difference. It should also be noted that green cloverworm populations did not increase in the field until two weeks after application. Such a trend would not have been predictable, and during winter meetings many entomologists across the country noted unusually high green cloverworm populations. Of note, green cloverworm populations were greatest at the same site, but crashed before causing significant defoliation. It is possible that some locations in the state experience more consistent insect pest pressure beyond those pests for which the life cycle predispose them to infesting certain fields (ex. Dectes stem borer, slugs). At no site did corn earworm or soybean looper reach treatable populations. Aggregating field sites together suggests that the risk of a pest population presenting in a field that could have been prevented is at most 1 out of 13. Yields were not significantly altered by the inclusion of the insecticide. Plot variation was generally greater than the yield value of the insecticide (between 0.1 and 0.25 bushels). Several factors affected plot yields, including soil/moisture variability, foxes, harvest equipment cutting angle relative to plots, degree of combine pass overlap, field edge effects, and herbicide drift or carryover from improperly cleaned tanks (which may have impacted one discarded plot at a Harrington site, 2021). These factors need to be more carefully considered during future studies. While inconclusive yield data was not entirely unexpected given the low yield difference necessary to justify inclusion of a pyrethroid in an already planned pesticide application, this work lays the foundation to continue similar trials with cooperator farmers. Over time and with many more site years, a stronger case for or against prophylactic insecticide application may be possible. 

Most of the spray timings targeted pre-reproductive stage soybean. Other common prophylactic application timings include R-stage fungicides and at planting seed treatments. Efforts can be expanded to include both of these timings in future studies. Similar continuing studies are being planned; overtime repeating these studies with cooperator farmers across the state will build a robust data set. 

Research conclusions:

This project sought to determine whether or not prophylactic insecticide application either with a herbicide or a fungicide application was justifiable in soybean. Such applications are made to an estimated 40% or more of the soybean acreage. This project installed strip trials at cooperator farms across Delaware. Farmers added a pyrethroid insecticide into their spray tank to treat full strips which were then scouted during the season for insect pests. Yield data was initially planned to be acquired from yield monitor data and to treat fields as replicates. The original plan was modified after yield analysis and discussion with agronomic extension faculty at the Carvel REC. 

At all sites, insect populations were below threshold at the time of application. Further, no significant yield differences were observed, suggesting that while prophylactic insecticide application may pay for themselves, they are unlikely to result in greater profit. The risk of having to make a follow up insecticide application that could have been prevented appears to be at most, equivalent to the cost of a follow up application. Thus, these treatments do appear to be neutral at best when insecticides are applied to vegetative stage soybean under relatively little stress. Changes in prophylactic insecticide use patterns will be quantifiable through end of the year pest loss surveys. This project will also be discussed in future extension publications and grower meetings. 

Participation Summary
10 Farmers participating in research

Education & Outreach Activities and Participation Summary

10 Consultations
10 On-farm demonstrations
4 Webinars / talks / presentations

Participation Summary:

10 Farmers
375 Number of agricultural educator or service providers reached through education and outreach activities
Education/outreach description:

Two virtual presentations at Delaware AgWeek were made, one in 2021 and one in 2022, which reached an estimated 150 stakeholders each. The project findings were discussed at two county meetings in 2021. The project was discussed with consultants and chemical company field scouts informally during the season. Results from 2020 are posted to the UD extension website and 2021 summaries will be available soon. Data summaries are being prepared for cooperating farmers. Prophylactic insecticide usage will be discussed in a planned fact sheet as well as in-season editions of the Delaware Weekly Crop Update, a digital blog that reaches over 750 unique email addresses. 

Learning Outcomes

10 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key areas in which farmers reported changes in knowledge, attitude, skills and/or awareness:

Regular conversations were held with eight cooperators and a consultant during the course of the project, and project results were used to inform management decision making of one farmer directly. No formal surveys were conducted to assess changes in knowledge or practice during the project time span. Project findings and summary will inform comments in the Delaware Weekly Crop Update during the 2022 season. Annual soybean pest loss surveys estimate that 37.9% of the acreage in 2020 received a prophylactic insecticide while in 2021 the estimate was 35%. Annual tracking will reveal whether or not a trend develops. It is possible though that if these practices are truly revenue neutral that they will continue with changes in commodity markets.

Project Outcomes

1 Grant applied for that built upon this project
1 Grant received that built upon this project
5 New working collaborations
Assessment of Project Approach and Areas of Further Study:

Study execution in 2020 was affected by  labor restrictions as a result of COVID-19 policies. Upon consultation with the UD agricultural engineer extension specialist, the study design was adjusted in order to obtain more rigorous and true yield data. There are several confounding variables that can impact yield estimates from farmer yield monitors that need to be carefully considered, including cutting swath uniformity, harvest angle relative to plots, presence of anomalous field features (ex water holes that reduced stand or yield), etc. Some of these considerations were addressed in 2021, including geo-referencing each spray strip, increasing the number of spray strips from one pair (originally envisioned that each field could serve as a single replicate) to three pairs, and using a weigh wagon at several locations. Future efforts are partially funded through the USDA-NIFA EIP program which funds multiple extension programs and activities, not just extension entomology. Through lessons learned during this project, additional, high quality site year data will be collected to more conclusively determine he potential benefit or lack of benefit of prophylactic insecticide application. At this time, and given the data that was collected, such practices cannot be promoted, but they do not appear to be financially prohibitive either. Other farm features should be considered (impact to beneficial insects, pollinators, and current insect pest population trends). Data collected are transferable to farmers across Mid-Atlantic, but especially those on the Delmarva peninsula. The Mid-Atlantic region generally has inconsistent insect pest incidences that justify stand alone insecticide application. Southern states have more consistent insect pest pressure, while northern states have consistent lack of insect pest pressure. The inconsistent insect pest populations in the Mid-Atlantic are precisely why this project was conducted at numerous cooperator sites, for it was hoped that with enough sites, more representative data could be collected than from one or two small plot trial locations with more controllable extraneous variables (but with lower likelihood of sustaining significant insect pests). Despite the trend towards lower pest populations in the Mid-Atlantic compared to southern states, many farmers include an insecticide application with herbicide application early in the season and with a fungicide application later in the season. This study focused on earlier, vegetative herbicide tank-mix timings and did not consider late season fungicide application timings save at one 2020 site. This is another treatment timing that should be investigated. 

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.