Results
In our vineyard, the first male grape root borer moths were recorded on July 5th (3 moths) and the last August 26th (1 moth), with the highest catch on July 15th with 127 moths. A total of 444 moths were captured in 2008, a 21.6% increase from the total captured (365 moths) in 2007. In 2006 a total of 243 male grape root borer moths were captured, in 2005 a total of 266 male moths were captured and in 2004 a total of 144 moths, while in 2003, 224 moths. This variability in the total number of male grape root borers captured each year is not unexpected. There is a very high mortality of eggs and newly hatched larvae that can vary significantly from year to year depending on many factors such as the weather and the presence of predators during egg development and hatching. In the northern regions of the grape root borer range (Pennsylvania) most of the larvae probably have a three year or longer life cycle.
Table 1. Major Catch Dates for 2008
Date Total moths captured
7-5 3
7-8 13
7-12 64
7-15 127
7-19 101
7-22 69
7-26 33
7-29 12
8-2 8
8-5 2
8-9 5
8-12 2
The initiation of moth emergence, date of highest catch and the end of moth emergence can also vary from year to year. During the six years of this project, the date of first capture has been from June 28th to July 5th. For five of the six years the date of the highest catch has been in mid-July with the other year being in early August. The date of last capture has varied from August 7th to August 30th.
Statistical analysis was performed on the data with two different methods in 2008. The first was the agricultural statistics analysis program (AgStats02) provided by the Pacific Northwest Conservation Tillage Systems Information Source at http://pnwsteep.wsu.edu/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 method was Tukey's studentized range (hsd ) test. This test is also called the honestly significant difference (hsd ) procedure.
The height treatment data in the statistical program has been entered as low (44 inches above ground level), medium (57 inches above ground level) and high (70 inches above ground level).
Table 2. Height Treatments 2008
high 70” 189 moths
medium 57” 128 moths
low 44” 127 moths
At a 5% level of significance, no significant difference was found in the 2008 height treatments with the AgStats02 program. The same result also occurred using Tukey's studentized range (hsd) test for statistical analysis. At a 5% level of significance, no significant difference was found in the 2008 height treatments. This was the first year since 2004 and the removal of the white traps from the study, that no significant difference was found in the height treatments.
Color treatments are entered in the statistical program as yellow, standard (yellow with green and white) and green.
Table 3. Color Treatments 2008
standard 221 moths
green 118 moths
yellow 105 moths
The experimental design for each color treatment (yellow, standard and green) 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, standard and green) were entered with nine replications. At a 5% level of significance, no significant difference was found in the 2008 color treatments with the AgStats02 program. The same result occurred in 2005, 2006 and 2007.
A different result occurred using Tukey's studentized range (hsd) test with 27 replicates for statistical analysis. At a 5% level of significance, a significant difference was found in the 2008 color treatments. The standard (yellow with green and white) traps were significantly better than the yellow traps.
Table 4. Tukey's studentized range (hsd ) test Color Treatment 2008
LSD (least significant difference) 3.8532
Treatment Name Mean
standard 8.1852 a treatments with different letters
green 4.3704 ab are significantly different
yellow 3.8889 b
5% level of significance
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 were all nine possible combinations of height and color treatments. Using AgStats02 at a 5% level of significance, no significant statistical difference was found in the 2008 combined treatments of height and color.
Based on statistical analysis in 2008, only the color treatments were significant. With Tukey's studentized range (hsd ) test, the standard (yellow with green and white)traps were significantly better than the yellow traps. This was the first year since 2004 the color treatments were found to be significant. In 2004 white traps were utilized instead of the current yellow traps. The white traps were removed from the testing in 2005 and replaced with the yellow traps. No statistical significance was found in the color treatments using the AgStats02 program.
The height treatments of 44 inches, 57 inches and 70 inches had no statistical significance in 2008. This was the first time since 2004 that no statistical significance was found in the height treatments. Every year since the white traps were removed from the experiment the height treatments had been significant.
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 the seyval and vidal.
In an analysis of variance (AgStats02) based on variety preference, two treatments 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, 2004, 2005, 2006 and 2007.
7. Conditions
On May 30, 2006, the adjoining 37 acre farm was sprayed entirely with a herbicide mix containing the amine form of 2,4-dichlorophenoxyacetic acid (2,4-D) because of its enrollment in the Conservation Reserve Enhancement Program (CREP) administered by the Farm Service Agency of the USDA. Grapevines are extremely sensitive to small amounts of phenoxy-type herbicides through both spray drift and volatilization of the chemical due to high temperatures. That day the high temperature reached 93°F for over one hour. By June 8th, herbicide damage due to 2,4-D was visible on the grapevines. On June 22nd, employees of the Pennsylvania Department of Agriculture took samples of grape tissue for herbicide testing. Analysis of the grape leaves found 2,4-D present at a concentration of 0.009 parts per million. A trace amount of 2,4,5-trichlorophenoxypropionic acid (2,4,5-TP), which was banned in 1985, was also found in the grape leaves. Damage from the herbicide exposure was more apparent in 2007, but still visible in 2008. Vine vigor and production of the chambourcin and vidal are below levels seen previous to the 2,4-D exposure. The seyval has rebounded to a vigor and production level equal to that found before the herbicide exposure.
A change in nozzle type in our vineyard sprayer during the first half of the season in 2008 resulted in an outbreak of powdery mildew.
8. 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 with some yearly fluctuations. Many other variables, such as weather or lack of disease pressure, could account for the 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. Since 2004, the production of chambourcin has remained relatively constant with minor fluctuations until 2007. Production of vidal increased each year since the project started until 2006. The decrease in vidal and chambourcin production can be attributed to the 2,4-D exposure in late May 2006. Vidal, with its reduced vigor, appeared to be the variety most affected by the exposure. Along with the decrease in fruit production, the chambourcin and vidal vines were less vigorous in 2007 and 2008 with decreased shoot growth and leaf production.
Table 5. Grape Production in Tons 2002-2008
Variety 2002 2003 2004 2005 2006 2007 2008
chambourcin 1.4 2.8 3.97 3.7 3.8 2.6 2.7
vidal 3.9 6.2 7.4 9.2 7.8 5.7 5.3