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Interactions on Mulch Color and 'Adios' On Cucumber Beetle Populations and Cantaloupe Production

M. D. Orzolek, S. J. Fleischer and L. Otjen,
Departments of Horticulture and Entomology
The Pennsylvania State University, University Park, PA 16802

Abstract

Application of colored mulches in vegetable crop production systems have resulted in both plant and pest responses. Current research at Penn State indicates that combining yellow mulch with insect baits enhances the control of cucumber beetles without reducing yield or quality of cantaloupes. In addition, the combination of yellow mulch and insect bait appears to reduce the mortality of honeybees from toxic insecticides.

Keywords

Polyethylene mulch, color, cantaloupe, insect pest management and biological materials

Introduction

Indications that insects were attracted by specific colors were confirmed by Ball (1982) when he placed Diabrotica virgerfera LeConte in choice boxes with different filters producing colors ranging from ultraviolet to red. He found that adult western corn rootworms were highly attracted to yellow compared to red, but red was more attractive than the other four colors in the test. In addition, visual cues have been used for the development of traps for monitoring (Hesler and Sutter, 1993). Black mulch alone has been shown to affect diabroticite immature densities in melon fields (Necibi et al, 1992). Comparing white, orange, yellow and aluminum, Csizinszky et al (1995) found the highest population of whiteflies (Bemisia argentifolii) and consequently virus were found on tomato plants grown on both yellow and white mulches. If in fact the color yellow attracts specific insects, can this color attraction be used in an IPM management program to reduce cucumber beetles and bacterial wilt infection in commercial cantaloupe production. Adios, an carbaryl based insecticide encapsulated within a feeding stimulant for Diabroticites, has been shown to effectively control adult cucumber beetle populations in commercial cantaloupe and cucumber fields.

Materials and Methods

Both black and yellow mulches from Rochelle Plastics were placed in the field with a 'Rainflo' bedder/mulch layer on May 9, 1995 at the Ag Progress Day Site, Russell E. Larson Research Center, Rock Springs, PA. The beds were placed on 7 foot centers and beds were formed to a height of 4 inches. Drip irrigation tubing was placed under the mulch (2"deep in the soil) at the same time the mulch was layed in the field. Cantaloupe plants, variety 'Cordele', were transplanted on June 2, 1995. Plants were spaced 2' in-the-row with five 40' rows comprising a single treatment. The field design was a Randomized Complete Block with 3 replications. Fruit harvested from the middle row of the 5 row plots were also sampled for soluble solids, flesh depth, and seed number/fruit. Fertilizer was broadcast at the rate of 600 lbs/A (10-10-10) on May 8, 1995 prior to forming beds and laying the plastic mulch in the field. Fungicides were applied as warranted when disease pressure exceeded threshold levels. Water was applied through the drip irrigation system approximately once a week from the end of July through late August. Adios was applied as broadcast spray over the treatment row of cantaloupes several times during the growing season.

Results and Discussion

The number of female flowers in each center data row per five row block were counted at weekly intervals from June 22 through July 12, 1995 (Table 1). The highest total female flower number was counted in cantaloupes grown on black mulch and fewest on the control plots. On June 22, plants grown on black mulch and treated with Adios had significantly more flowers than the control but similar to the other treatments. On July 7, plants grown on yellow mulch and treated with Adios had significantly more flowers than the control but similar to the other treatments. At the same time as number of female flowers were being counted, the number of young, developing fruit was also counted from June 29 to July 20 (Table 2). The highest total number of developing fruit was counted in cantaloupes grown on black mulch and fewest on the control plots. Both on July 7 and 12, plants grown on yellow mulch and treated with Adios had significanlty more flowers than the control but similar to the other treatments. Ironically, the percent of fruit set , based on the data from tables 1 and 2, is highest in the control - 75.7% followed by the yellow plus Adios treatment - 73.8% and least in the black plus Adios treatment - 50%. It is apparent from the total number of fruit harvested from the center data row of each replication that far more flowers and fruit are set than ever reach maturity. Plants have to maintain a specific sink to source relationship throughout the growing season. Developing fruit, flowers, and young expanding leaves all require re-allocation of carbohydrates produced through photosynthesis during the day. However, when demand for carbohydrates exceeds daily production, the plant will abort either flowers or young developing fruit to maintain their carbohydrate balance within the plant to survive.


When evaluating data from the center row of the five row plot, cantaloupes grown on the polyethylene yellow mulch in which Adios was applied produced a significantly larger yield than cantaloupes grown on yellow mulch alone or black mulch with Adios (Table 3). There was no difference in yield between cantaloupes grown on black mulch alone and cantaloupes grown on yellow mulch and Adios. Ironically, applying Adios to melon plants grown on yellow mulch increased yields compared to yellow alone whereas applying Adios to melon plants grown on black mulch decreased yields compared to black alone. There were no differences between treatments for average fruit weight, depth of fruit flesh, percent soluble solids or seed number per fruit.


When the data was analyzed on the entire five row plot, the same yield difference was observed as that found in the center row data analysis (Table 4). Again, applying Adios to melon plants grown on yellow mulch increased yields compared to yellow alone whereas applying Adios to melon plants grown on black mulch decreased yields compared to black alone. Also, as in the single row plot analysis, there were no differences between treatments for average fruit weight, depth of fruit flesh, percent soluble solids or seed number per fruit.


There was a higher plant mortality from bacterial wilt in cantaloupes grown on all the treatments compared to the control (Table 3). The weekly application of pyrethroids successfully controlled cucumber beetles and their feeding so that no bacterial wilt was observed in the control throughout the growing season. Even with 30% plant mortality due to bacterial wilt, melon yields were still within standard yield range for this cultivar (6,000 to 8,000/A). The number of infected beetles per acre, stage of plant development, growth under stress conditions, planting date and cultivar maturity all influence the extent of yield loss from bactrial wilt infection throughout the growing season.


Of the 2,627 beetles counted during the growing season, 94% were striped cucumber beetles, and only striped beetle densities are reported in this paper. The live beetle densities (Fig 1) suggest three peaks, clearly showing that in-field reproduction was occurring: an early peak from immigrating adults (approximately 160 julian days ), a midseason peak ( approximately 175-180 julian days), and a late season increase that continued past the time of data collection. The immigrating adults were mostly in the treatments with yellow mulch, suggesting that they were attracted or arrested by the yellow color. The midseason adult densities were higher in the control versus the Adios-treated plots, and the effect of mulch color appears to have a diminished response. Late in the season, another generation appeared, and the rise in adult density was occurring in both control treatments but not in the Adios treatments. The rise in beetle densities was occurring faster in the treatments with the yellow mulch.


The proportion of beetles collected that were dead was also plotted for the season (Fig. 2). This data might be viewed as a measure of efficacy; that is, of the total beetles collected, what proportion were dead. The black mulch/no pesticide treatment had virtually no efficacy. The Adios treatments varied in efficacy from very low to almost 100% control. The drop in efficacy (that is, a drop in killing off a high proportion of beetles) seemed to follow a seasonal pattern, with peak depressions during two time spans. Both of these times correspond roughly to the end of one generation (i.e., 'old adults') and the early part of the emergence of a new generation (i.e., very young adults). However, this phenomena could also have been due to the effects of weather during the 1995 growing season.

Conclusions

  1. Yellow mulch significantly attracted more immigrating populations of striped cucumber beetles than black mulch. When combined with the feeding stimulus Adios, the yellow mulch-Adios treatment produced effective control of cucumber beetles.
  2. More flowers and fruit were produced from plants growing on the treatments compared to the control. The number of flowers or fruits counted on plants varied from week to week and were dependent on the environmental conditions and the current carbohydrate demand within the melon plant.
  3. Highest yield of cantaloupes was harvested from the yellow mulch-Adios treatment compared to the other treatments, but was not significantly different from the black mulch alone treatment. Combining Adios with yellow mulch significantly increased yields compared to yellow mulch alone whereas combining Adios with black mulch decreased yields compared to black mulch alone, but not significantly.
  4. Bacterial wilt infection from striped cucumber beetle feeding on the melon plants was relatively high throughout the growing season. Fortunately, plant mortality from bacterial wilt depends on the number of infected beetles per acre, stage of plant development, plant growth under stress conditions, planting date and cultivar maturity.

Literature Cited

  • Ball, H. J. 1982. Spectral response of the adult western corn rootworm (Coleoptera: Chrysomelidae) to selected wavelenghts. J. Econ. Entomol. 75:932-933.
  • Csizinsky, A. A. 1995. Evaluation of color mulches and oil sprays for yield and silverleaf
    whitefly control on tomatoes. HortScience. 30(4):755
  • Hesler, L. and G. R. Sutter. 1993. Effect of trap color, volatile attractants, and type of toxic bait dispenser on captures of adult corn rootworm beetles (Coleoptera: Chrysomelidae). Environ. Entomol. 22:743-750.
  • Necibi, S., B. Barrett and J. Johnson. 1992. Effects of a black plastic mulch on the soil ans plant dispersal of cucumber beetles, Acalymma vittatum (F.) and Diabrotica undecimpunctata howardii Barber (Coleoptera: Chrysomelidae) on melons. J. Agric. Entom. 9:129-135.
  • Orzolek, M. D. 1993. The effect of colored polyethylene mulch on the yield of squash and pepper. Proc. Natl. Agr. Plastics Congr. 24:157-161.

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Table 1. The number of female flowers counted each week (June 22 to July 12) for 'Cordele' cantaloupes grown on yellow and black mulch and treated with Adios at the Russell E. Larson Research Center, Rock Springs, PA - 1995.

Treatment June 22 June 29 July 7 July 12 Total Number
Yellow 10 2 11 40 63
Black 16 7 10 42 75
Yellow + Adios 11 8 14 28 61
Black + Adios 18 6 10 30 64
Control 5 3 5 24 37
LSD.05 10 NS 6.8 NS

Control - cantaloupes grown on black mulch and sprayed weekly with Asana.

 

Table 2. The number of developing fruit counted each week (June 29 to July 20) for 'Cordele' cantaloupes grown on yellow and black mulch and treated with Adios at the Russell E. Larson Research Center, Rock Springs, PA - 1995.
____________________________________________________________________________

Treatment June 29 July 7 July 12 July 20 Total Number
Yellow 6 1 9 27 43
Black 7 1 8 34 50
Yellow + Adios 7 1 12 24 45
Black + Adios 4 0 7 21 32
Control 3 0 4 21 28
LSD.05 NS 1.5 6.1 NS

Control - cantaloupes grown on black mulch and sprayed weekly with Asana.

Table 3. The marketable yield, average fruit weight, percent soluble solids, flesh depth, and plant mortality (from bacterial wilt) of 'Cordele' cantaloupes grown on yellow and black mulch and treated with Adios and harvested only from the center row of the 5-row plots at the Russell E. Larson Research Center, Rock Springs, PA - 1995.

Treatment Marketable yield
Avg fruit
weight (lbs)
Soluble solids
%
Flesh depth
(cm)
Plant mortality
(% BW)

No.
Wt.(lbs)
Yellow
25
96.3
3.9
11.8
3.6
33
Black
30
109.5
3.6
12.0
3.4
30
Yellow + Adios
36
134.3
3.8
12.1
3.5
28
Black + Adios
24
93.1
3.9
11.4
3.7
33
Control
25
99.3
4.0
12.1
3.7
0
LSD.05
10
32.4
NS
NS
NS

Control - cantaloupes grown on black mulch and sprayed weekly with Asana.

Table 4. The marketable yield, average fruit weight, percent soluble solids, flesh depth, and number of seed per fruit of 'Cordele' cantaloupes grown on yellow and black mulch and treated with Adios from the entire 5 row plot at the Russell E. Larson Research Center, Rock Springs, PA - 1995.

Treatment Marketable yield
Avg fruit
weight (lbs)
Soluble solids
%
Flesh depth
(cm)
Seeds #
per fruit

No.
Wt.(lbs)
Yellow
134
499.6
3.7
11.8
3.6
520
Black
157
582.4
3.7
12.0
3.4
537
Yellow + Adios
176
666.3
3.8
12.1
3.5
545
Black + Adios
137
522.5
3.8
11.4
3.7
506
LSD.05
33
137.5
NS
NS
NS
NS

Figure 1. The number of dead striped cucumber beetles A. vittata counted in 'Cordele' cantaloupes grown on yellow and black mulch with and without Adios application at the Russell E. Larson Research Center, Rock Springs, PA - 1995.

Figure 2. The proportion of dead striped cucumber beetles A. vittata to total beetles counted in 'Cordele' cantaloupes grown on yellow and black mulch with and without Adios application at the Russell E. Larson Research Center, Rock Springs, PA - 1995.