THE AGRICULTURAL RESEARCH FOUNDATION FOR Regional Pest Monitoring Program

Size: px
Start display at page:

Download "THE AGRICULTURAL RESEARCH FOUNDATION FOR Regional Pest Monitoring Program"

Transcription

1 RESEARCH REPORT TO: THE AGRICULTURAL RESEARCH FOUNDATION FOR 2012 TITLE: Regional Pest Monitoring Program RESEARCH LEADER: Daniel McGrath PHONE: COOPERATORS: Manual Silveira and Jim Gill, NORPAC; Wayne Parker, Jason White, and Neil MacInnes, National Frozen; Ron Pearmine, Tom Barnett, Mark, Mike, and Cory Dickman, Skip Gray, Oscar Lopez, Matt and Gary Cook, Karl, Nancy, and Kenny Hendricks, Tom and Sam Sweeney. Technical support for this project was provided by Pami Opfer and Alejandro Gonzales. This Report is also submitted to the Oregon Processed Vegetable Commission Broccoli and Cauliflower, Corn and Bean Research Committees. Introduction ~ Regional Pest Monitoring VegNet is a regional pest monitoring and reporting network serving the Oregon processed vegetable industry, managed by the OSU Extension Service, and funded by the Oregon Processed Vegetable Commission. In the early spring of 2012, thirty six insect monitoring stations were established on cooperating farms located strategically throughout the Willamette Basin and maintained during the growing season. Farms were monitored with pheromone traps for adult insects (cabbage looper, cabbage white butterfly, diamondback moth, Bertha armyworm, black cutworm, corn ear worm, 12 spot beetles, and variegated cutworm). Selected broccoli and cauliflower fields were scouted for the immature stages of the lepidopteron pests and the cabbage aphid. Selected fields were scouted for 12 spot beetles using a standard sweep net sampling technique. Insect samples from were collected during the growing season 1

2 from cooperating processors to determine which insect contaminates were intercepted by quality assurance programs. VegNet newsletters were distributed to three hundred and twenty (320) growers and agricultural professionals and posted on the OSU Vegetable Website. The newsletters are like an insect weather report. They give growers advanced notice of pest population trends. They serve as vehicle to get out other timely information. VegNet narratives emphasize that the best pest control decisions are made on the basis of field-specific scouting results. Regional pest monitoring helps growers and agricultural field representatives to adjust their scouting effort when an outbreak is detected. The combination of regional monitoring plus field-specific scouting reduces risk of crop loss. On some occasions, the combination of regional monitoring and field-specific scouting provides opportunities to reduce insecticide applications when pest pressure is very low. Regional pest trends serve as an early warning system which signals (high or low) when field-specific scouting efforts should be intensified. The goals of the VegNet Regional Pest Monitoring and Reporting System are: 1) to save growers money by providing them with advanced notice of population outbreaks for key vegetable pests in broccoli, cauliflower, snap beans, and sweet corn 2) to demonstrate the commitment by the Oregon Processed Vegetable industry to integrated pest management strategies for protecting crops and the environment 2

3 Results Part One ~ Broccoli and Cauliflower Pests Four Lepidopteron insects and one aphid species damage and contaminate broccoli and cauliflower: diamondback moth (Plutella xylostella), cabbage white butterfly (Pieris rapae), Bertha armyworm (Mamestra campestra), cabbage loopers (Trichoplusia ni), and the cabbage aphid (Brevicorynae brassicae). The Cabbage Looper (Trichoplusia ni) has two distinct generations per growing season. Due to the cool, wet spring, Cabbage Looper population development was delayed. Moth counts were very low compared to the ten year average in the Willamette Valley (Figure One). Cabbage White Butterfly (Pieris rapae) counts were very low through most of the early part of the growing season. We believe this was due to a delay in the population development due to the cool wet spring. By the time the butterfly counts went up, much of the broccoli was harvested (Figure Two). Diamondback moth (Plutella xylostella) have six or more overlapping generations per growing season. Winter weather determines if the population survives in the Willamette River Basin, or must recolonize from the south in the spring. Diamondback 3

4 moths are weak fliers. To detect their presence, paper wing traps must be placed in the field at the height of the broccoli and cauliflower plants. Diamondback moth counts were delayed in 2012 (Figure Three). We believe the delay was caused by the cool temperatures in the spring rather than a failure to survive over the winter. Even though Diamondback moth counts were at normal levels, Diamondback pupa still made up a significant percent of the insect contamination of broccoli and cauliflower during 2012 growing season. Bertha Armyworm (Mamestra campestra) contaminates a variety of crops including bell pepper, hops, potatoes, sugar beets, alfalfa grown for seed, and even some tree fruits. It can contaminate broccoli and is difficult to detect in the field. The moth deposits egg clusters dispersed widely in the field. The larvae remain on a single plant until they mature, at which point they disperse in the field. Suddenly, the field is contaminated. Bertha Armyworm moths can be detected using the wire mesh Texas style haystack traps placed at the edge of the field. Bertha Armyworm has two distinct generations per growing season. Moth counts were delayed and below average during 2012 growing season (Figure Four). 4

5 Alfalfa Looper (Autographa californica) is attracted to the same pheromones as the Cabbage Looper, so one needs to be able to distinguish between the species in the pheromone traps. Alfalfa Looper, during an outbreak, can contaminate cole crops. It can defoliate alfalfa, peas, sugar beets, beans, mint, and spinach. Alfalfa looper moth counts were delayed and below average (Figure Five). Varigated Cutworm (Peridroma saucia) is attracted to the same pheromone as Bertha Armyworm, so one needs to be able to distinguish between the species in the pheromone traps. During an outbreak, Varigated Cutworm can defoliate alfalfa, clover, sugar beets, mint, and vegetables including beans, beets, spinach, lettuce, and peas. Varigated Cutworm moth counts were very low during the 2012 growing season (Figure Six). Field scouting plus regional pest monitoring generally do not lead to no-spray decisions because the probability of all five contaminating insect populations reaching low levels during the same growing season is very low. However, regional pest monitoring does lead to reduced number of insecticide applications. The 2012 growing season was a good example. Insect pressure was low. Many growers used a single application of insecticide to control aphids and worms in broccoli. No truckloads of broccoli or cauliflower were rejected during the 2012 growing season due to insect contamination. 5

6 On the other hand, regional pest monitoring can protect growers during single and multiple species outbreaks. When two or more contaminating insect populations are in an outbreak, the total worm load in broccoli and cauliflower can be very high. Most insecticides kill about 98% of their target population. In a normal year, the residual surviving worms are so low that it is below the detection level. In an outbreak year for one or more contaminating insects, the residual two percent surviving worms are high enough to result in truckload rejections. In an outbreak, a minimum of two insecticide applications are required. Regional pest monitoring for broccoli and cauliflower pests is focused on detecting outbreaks, signaling growers and agricultural professionals when to intensify their field scouting, and when to increase their aggressiveness in preventing crop losses. No truckloads of broccoli or cauliflower were rejected due to insect contamination during the 2012 growing season (Table One). Table One: Broccoli Loses Due to Looper Contamination Willamette Valley, Oregon 1998 to 2011 Year Moth Counts Totes 1) Rejected Loses Adjusted 2) by Volume ($/5,000Tons) 1998 moderate 313 $18, low 20 $1, high 63 $8, moderate 24 $2, high 235 $17, low 0 $ low 0 $ high 0 $ high 0 $ moderate 0 $ low 0 $ low 0 $0 1) Totes of broccoli rejected due to Cabbage looper contamination. 2) Dollar loses per ton of broccoli, average raw-product prices. 6

7 Results Part Two ~ Snap Bean Pests Twelve Spot beetle populations are monitored on a regional basis with yellow sticky traps. Spray decisions are based on site specific sampling with a sweep net. Traditional sweep net sampling produces single point in time beetle count. Yellow sticky traps produce continuous sampling data. This reveals the life cycle of the beetle (Figure Seven). There is early spring activity when the female beetles come out of winter hibernation. After laying their eggs, these beetles die. The above ground population of beetles disappears. The population goes underground where the larvae of the beetles eat the roots of several vegetable crops including sweet corn. In mid-july, the first summer generation of twelve spot beetles emerges from the soil. The gender ratio (males to females) returns to normal. The second generation of beetles emerges from the soil in October and over winters. The male beetles are smaller bodied and tend to die off during the winter. The female beetles survive the winter and reemerge the following spring. 7

8 The progress of the twelve spot beetle population life cycle can be detected on a regional basis. During the sustained period of low beetle pressure in a normal year, early bean plantings flower and escape beetle damage. A grower can make a double safe no spray decision. If they sample a bean planting with a sweep net and find very few beetles, and if there are very few beetles in the surrounding landscape, one can skip the insecticide application with very low risk of crops damage. The twelve spot beetle population followed this typical pattern during the 2012 growing season (Figure Eight). Results Part Three ~ Sweet Corn Pests Cutworms are hard to detect in the field because early cutworm instars are small, graybrown in color, and subterranean. Significant cutworm moth egg laying flights, on the other hand, are easy detect. Black cutworm outbreaks occur about once per decade. The last major Willamette Valley black cutworm outbreak occurred in Black cutworm moth counts took off sharply in late May during the 2012 growing season (Figure Nine). We thought we might be in for an outbreak. Instead, the moth counts dropped back to normal and the outbreak did not materialize. 8

9 The false corn earworm moth (Heliothis phloxiphaga) is attracted to the same pheromone as the Corn Earworm moth (Heliothis zea). One needs to be distinguish between the species in the pheromone traps. Heliothus phloxiphaga during an outbreak can be a problem in ornamental crop nurseries. Corn earworm moth counts and Heliothis phloxiphaga were delayed and average on a regional basis during the 2012 growing season (Figure Ten and Eleven). Fresh market growers generally apply an insecticide spray at first silk regardless of moth counts. Subsequent sprays are based on pheromone moth trap counts. In some fresh market production systems, an action threshold for the second and subsequent insecticide applications is five moths per trap per day. Conclusion The VegNet regional pest monitoring program sponsored by the Oregon Processed Vegetable Commission, on occasion, has saved growers money by providing growers and agricultural professionals with early warnings of insect pest outbreaks. The warnings prompted increase field scouting. Increased field scouting led to more aggressive spray programs. This has significantly reduced the amount of broccoli rejected due to insect contamination even during high pressure years. The combination of regional pest monitoring plus field scouting has allowed growers, in some cases, to reduce insecticide applications without significantly increasing risk 9

10 of crop damage. We have demonstrated that when field-specific scouting shows that the beetle counts in a bean fields is low at the same time that the regional population trend for the beetles is also low, it is reasonably safe to skip the insecticide. Processors have taken advantage of this integrated pest management program in their stewardship marketing campaigns. If we are going to claim that we are good stewards of the food system, we need to use proven field scouting and pest monitoring techniques to justify when sprays are needs. Occasionally, we can skip a spray without putting the crop at risk. Our hope is that an authentic stewardship program may help Oregon processors to maintain market shares with national brokers of processed food who are aggressively looking for ways to protect and enhance their brand image. The VegNet Newsletter, which is widely circulated in the Willamette Basin serves as a platform for dealing with new issues that arise during the growing season. 10