Control of Grape Root Borer

[The full report with tables is available from the NE SARE office in Burlington, VT]

Project Contact

Name: R. Martin Keen
Organization: Landey Vineyards
Mailing address: 411 South Queen Street
Lancaster, PA 17603-5617
Phone number: (717)394-3893
E-mail: growsaffron@juno.com

Report Summary

Grape root borer is one of the most serious insect pests of grapes in the eastern United States. The goal of this project is to find a sustainable method of control using pheromone traps. Three different colors (standard-yellow with green and white, all green and all white) of traps placed at three different heights were located in the vineyard using a randomized complete block design. A total of 81 traps were placed in the experimental area of 2.41 acres in the three acre vineyard. The yellow (standard) traps were found to be statistically better at capturing grape root borers than the green or white. Placement of the traps has rarely been found to be statistically significant, although traps positioned at the top of the trellis have consistently captured the most moths. The total number of moths captured decreased 36% from the first to the second year of this project. During the same time period, production of grapes has increased. If current trends continue, mating disruption and control of grape root borer appears possible.

Goals

Little work has been done on the grape root borer in Pennsylvania. Several methods are available to trap and enumerate the adult male grape root borer with pheromone lures. We have worked with different trapping methods in our vineyard. In 2003 a Northeast SARE project (FNE03-471) was initiated in our vineyard. The results of this project revealed the color of the trap is a significant parameter in the number of moths captured. Also the project revealed there was no significant difference between the different height placements. The current SARE project was undertaken to validate the results from 2003. One of the main goals of the project will be to ascertain if mating disruption is possible with high numbers of pheromone traps in a vineyard. Because of the multiyear life cycle of the grape root borer an extended testing period of several years is required. If mating disruption is possible as a control measure, the need for pesticides would be eliminated.

Farm Profile

I am a part-time farmer currently farming 5 acres with my brother. The land is rented from our mother. The total size of the present farm is only 7.8 acres, although it has been cultivated by our family for seven generations. There is no house on the premises, only a 40' by 60' tobacco barn. My brother and I first planted wine grapes on the farm in 1974. Today a total of 3.5 acres is planted in wine grapes and includes the French hybrids: seyval, vidal and chambourcin. The vines are grown with unilateral or bilateral cordon training on the bottom wire. A standard three wire system with wires at 36, 54, and 72 inches is used for the trellis. The vines are trained using vertical shoot positioning. Vineyard spacing is 9 foot wide rows with 6 feet between the vines in the row. An area of approximately one half acre is used for the growing and production of grafted vines and other varieties. Since 1989 I have also grown one half acre of saffron on the farm. Currently I am the only commercial grower of saffron in the United States.

The farm is composed entirely of Duffield silt loam with a 0 to 3% slope on the top of a small hill. The location provides excellent air drainage with no frost pockets. The surrounding area is almost entirely in farmland and is located in an agricultural security area. There have been no changes in the operation since the initiation of the SARE project.

Participants

The technical advisor for this project is Mark Chien of Pennsylvania State University. Since 1999, Mark has been the wine grape agent for Perm State Cooperative Extension, serving a 15 county region in southeastern Pennsylvania. Another advisor on the project is Dr. Michael Saunders of the entomology department at Pennsylvania State University. One area of his research involves the ecology and pest management of arthropods affecting vineyards and refining existing grape management practices. His extension work covers integrated pest management in viticulture. Dr. Saunders will provide expertise in experimental design and statistical analysis of the data.

Project activities

The results from the 2003 SAKE project (FNE03-471) revealed the color of the trap can be significant in the number of moths captured. The goals were to maximize the capture rate by determining the best color and placement of traps and to ascertain if mating disruption is possible with a high number of traps. The experiment was designed to attempt capture of all male moths with sufficient replicates for statistical analysis. In 2003, 31% of the traps caught no root borers at all and four traps or 5% were responsible for capturing 25% of the moths. The experiment from 2003 was repeated in 2004 using the same plots and blocks with the traps placed in a new random selection. The variables tested were trap color and placement. A randomized complete block design was developed for each variable. The experimental area covered 80% of the vineyard.

Three different trap colors were selected for the test, green, white and the yellow trap with green top and white bucket also known as the standard trap. The plastic universal moth traps available from Great Lakes IPM were utilized. These were the same traps used in 2003. A white trap was not available, consequently the green top and yellow funnel section of the yellow (standard) traps were spray painted white with semi-gloss paint. A total of 81 traps were placed in the vineyard or 27 each color: green, yellow and white.

The vineyard was divided into 27 blocks of 72 feet by 54 feet or 3888 square feet per block. Each block was divided into three plots of 18 feet by 72 feet or 1296 square feet per plot. A trap was suspended on the trellis at the center of each plot. Every block received the three different colors. The color of each trap placed in the plots of each block was selected using a ten thousand random digit table.

Three different trap height placements were selected for the test. Traps were placed 18 inches above the ground or below the vine canopy, 44 inches above the ground or in the middle of the canopy close to the fruiting zone and 70 inches above the ground or at the top of the vine canopy. The distance from ground level was based on the position of the pheromone lure.

For trap height the vineyard was divided into 9 blocks of 162 feet by 72 feet or 11,664 square feet per block. Each block was divided into three plots of 72 feet by 54 feet or 3888 square feet per plot. Each plot for the trap height experiment was the same as a block for trap color. Within each plot for trap height, the three traps all received the same height. For each of the three trap heights there were 27 replicates, three in each plot. The height of the traps in the plots of each block was selected using a ten thousand random digit table.

The traps were placed in the vineyard on June 21st according to the experimental design. A 10% DDVP toxicant insecticide PVC tape measuring 1 inch by 4 inches was placed inside each trap to kill any moths that entered. A pheromone lure for grape root borer was placed in the lure holder for each trap. The traps were checked every three or four days or twice a week from June 21st until September 4th and the moths captured were recorded on data sheets.

Results

The first grape root borer moth was recorded on June 29th and the last August 7th, with the highest catch on July 13th with 33 moths. A total of 144 moths were captured in 2004, a 36% decrease from the total captured in 2003.

Table 1. Major Catch Dates for 2004

Date Total moths captured
6-29 1
7-3 7
7-6 11
7-10 31
7-13 33
7-17 23
7-20 15
7-24 12
7-27 8
7-31 2

In 2003 the first moths were captured on June 28th (2 moths) and the last August 30th, with the greatest number of moths recorded on August 2nd with 96 moths.

Statistical analysis was performed on the data with two different programs. The first was the agricultural statistics analysis program (AgStats02) provided by the Pacific Northwest Conservation Tillage Systems Information Source at http://yolo.usda-ars.orst.edu/steep/AgStatsweb/. This program allows up to 16 treatments and 16 replicates and performs an analysis of variance. The level of significance can be selected at 1%, 5%, 10% or 20%. All data entered with this program utilized the randomized complete block design option. The other statistical program was SAS/STAT from the SAS Institute performing an analysis of variance and Tukey's studentized range (hsd) test. This test is also called the /zonestly significant difference (hsd) procedure.

The height treatment data in the statistical programs has been entered as low (18 inches above ground level), medium (44 inches above ground level) and high (70 inches above ground level).

Using the Agstats02 with nine replicates, the high placement at 70" was significantly better than the medium or low with a 5% level of significance.

No significant difference was found in the 2004 height treatments using 27 replicates with Tukey's studentized range (hsd) test at a 5% level of significance.

Color treatments are entered in the statistical programs as green, yellow (standard-yellow with green and white) and white.

The experimental design for each color treatment (yellow, green and white) contained 27 replicates. Unfortunately the AgStats02 program allows only 16 replicates. To run this program the three replicates of each color in each height block were combined. The three treatments (yellow, green and white) were entered with nine replications. At a 5% level of significance, the yellow traps were significantly more effective than the green or white traps.

With the Tukey's studentized range (hsd) test using 27 replicates, significant differences were found in the color treatments. The yellow traps were significantly better than the green or white.

An analysis of variance (AgStats02) for the combined treatments (height and color)was performed. For this statistical analysis nine treatments were entered with nine replications. Within each height treatment block (162 ft. by 72 ft.) there are all nine possible combinations of height and color treatments. At a 5% level of significance the high yellow traps were significantly more effective than any other height and color combination.

Based on statistical analysis, the height treatments may or may not be significant. Only the AgStats02 program in 2004 showed any significance with the high better than the medium or low. No statistical significance was found in 2003. Testing will continue in coming years on the possible significance of placement. Each year the high traps have caught the greatest number of moths, but not always in significant numbers.

The color treatments have shown a statistical significance in 2003 and 2004. In 2004, the yellow (standard-yellow with green and white) traps were statistically better than the green or white. Yellow traps have captured the greatest number of moths each year. The white traps have consistently caught the lowest number of moths and have been the poorest statistically.

Three varieties of French hybrid grapes; seyval, vidal and chambourcin are planted in the vineyard. The experimental design was developed primarily to test if adult male grape root borer moths would have a preference for different pheromone traps based on color and location. The initial plan called for an attempt to determine if grape root borers have a preference among the three varieties planted in our vineyard. Unfortunately the experimental design only allows a comparison to be made between seyval and vidal.

In an analysis of variance (AgStats02) based on variety preference, two treatments (seyval and vidal) were entered with eight replicates. No significant difference was found between the two varieties even at a 20% level of significance. The same result occurred in 2003.

Economics

Although the project was not structured for economic analysis some trends are apparent. Since the introduction of universal moth traps to the vineyard, production has increased. Many other variables, such as weather or disease pressure, could account for this increase, instead of the presence of moth traps. With the increase in production, total farm income has also increased. The production of chambourcin, our most valuable variety, peaked in 1996 at 5.5 tons total production. By 2002 when two universal moth traps were placed in the vineyard, production had declined to 1.4 tons. Over the next two years, when 81 traps were in the vineyard each year, production increased 184% to 3.97 tons.

Assessment

The results from 2004 validated the results from 2003. No statistical significance was found in the different height treatments in 2003. A significant difference was found in the height treatments in 2004 with the AgStats02 program, but not with Tukey's studentized range (hsd) test. With the AgStats02 program the high traps were better than the low or medium placed traps. Each year the high traps have caught the greatest number of moths , but rarely in significant numbers. Testing will continue in coming years on the possible significance of placement.

The color treatments have shown a statistical significance each year. Yellow (standard-yellow with green and white) traps have captured the greatest number of moths each year and statistically are better than the white or the green and white traps depending on the year. The white traps have consistently captured the lowest number of moths and have been the poorest statistically. A white color appears to inhibit capturing the maximum number of grape root borer moths. Although white paper wing traps have been used extensively in grape root borer research, there use should be limited to general survey work. Other colors of traps will be tested in the future. An all yellow trap with no other colors will be added to the project in 2005.

Distribution of the grape root borer in a small area is very random. In the experimental test area of 2.41 acres, there were plots with no root borers and other areas of higher concentrations. In both 2003 and 2004, 25 traps or 31% caught no root borers during the 2.5 months of trapping. The plots with the highest concentrations of captured moths were lower in 2004 as compared to 2003. In 2004, 4 traps or 5% captured 20% of the moths and the two highest trap counts were 8, followed by 7 and 6. The four highest trap catches in 2003 were 17,15, 14 and 10. The high number of traps with no catches would indicate the vast majority of the moths are probably captured in a relatively short period of time close to the area where they emerge.

Adoption

The results after two years of the project are encouraging. The yellow (standard-yellow with green and white) traps have captured significantly more moths than the green or white. The yellow color appears to be significant in the capture of grape root borers. In 2005 an entirely yellow trap will be added to the project and white traps will not be used. The high placement of traps has consistently captured the greatest number, but rarely in significant quantities. Testing will continue with all three height placements to check if any additional statistical significance occurs.

Mating disruption appears to be a possibility. The total number of moths captured each year is decreasing. In 2002 with two universal moth traps, a total of 239 moths were captured. With the introduction of 81 traps to the vineyard in the 2003 SAKE project, 224 male moths were caught. The following year in 2004, 144 moths were captured, a 36% decrease in one year. During the same period grape production has increased. Chambourcin went from 1.4 tons in 2002 to 3.97 tons in 2004 and vidal increased from 3.9 tons to 7.4 tons in the same time period. If the current trends continue in future years of testing, the mating disruption and control of grape root borer appears possible with the proper placement and color of traps.

Outreach

A forty-five minute power point presentation on the 2003 and 2004 SARE projects was given at the 2005 Mid-Atlantic Fruit and Vegetable Convention on February 1, 2005 in Hershey, Pennsylvania. The meeting is sponsored by the State Horticultural Society of Pennsylvania, Pennsylvania Vegetable Growers Association, Maryland State Horticultural Society and New Jersey State Horticultural Society. Approximately 100 people attended the talk. A six page report based on the 2003 and 2004 SARE sponsored research was written for inclusion in the proceedings of the meeting published by the State Horticultural Society of Pennsylvania. The report was also sent to the New Jersey Horticultural Society for their publication, New Jersey Horticultural News.

Mark Chien, wine grape agent for Perm State Cooperative Extension also included the six page report in his electronic newsletter, Wine Grape Information for Pennsylvania and the Region. This electronic newsletter is sent to approximately 300 grape growers in the area.

On June 18, 2005 a forty-five minute presentation on the 2003 and 2004 SARE projects will be given at the summer field day of the Maryland Grape Growers Association held in Westminster, Maryland.

R. Martin Keen
April 27, 2005