Cabbage Pests Research Articles

Evaluation of Microbial and Insecticide Combinations for the Control of Cabbage Pests in Minnesota, 1991

Abstract This test was conducted on the University of Minnesota Agricultural Experiment Station at Rosemount in cabbage transplanted on 14 Jun. Plots were two rows on 36" centers, 40 ft long, and separated by 7 ft alleys on the sides and 10 ft alleys at the ends. They were arranged in a randomized complete block design with 4 replications. A Spirit sprayer with 5 hollow-cone (TX-10) nozzles/2 rows, delivering 27 gal/acre at 45 psi, was used to treat each plot. Two plots (MVP & Ambush early) received 5 sprays while the remaining plots received only 4. Treatments were applied 27 Jun (MVP & Ambush early plots only), 17, 24, 31 Jul, and 14 Aug. Evaluations of larval numbers, aphids, and beneficials were made on 13 Aug by randomly selecting 5 heads/plot. Damage and marketability ratings were made on 29 Aug by randomly harvesting 5 heads/plot.

Variable-Intensity Sampling for Proportion of Plants Infested with Pests

Construction of a variable-intensity sampling procedure for binomial data is described. Performance of an algorithm to calculate sampling intensity, which can be programmed into a portable computer for use in the field, was compared with that of a chart for determining sampling intensity, and was found to differ little. In computer simulations, performance of the procedure on the binomial distribution, using the algorithm described, was similar to that for previously described performance on the negative binomial distribution. Simulated between-site variation in the proportion of plants infested had little effect on the sample size or estimates of the average proportion infested. Simulated edge effects, higher proportion of infested plants at the edge of the field, increased overestimation; simulated patterns of infestation resulting from a clogged sprayer nozzle increased underestimation, but this bias would not affect treatment decisions. Testing the procedure on field data for five pests of cabbage resulted in performance similar to the simulations. Variable intensity sampling for proportion of plants infested with pests could be the most useful procedure to use when samples must be taken along the entire length of a transect, yet total sample size must be chosen efficiently.

Constraints to IPM development and a strategy for management of tomato and cabbage pests in Trinidad, West Indies

Abstract Despite high social and economic costs resulting from pesticide use, farmers in many developing countries still persist in this method of pest control. One reason is the perception that the development and implementation of IPM strategies are beyond their capabilities. Using the example of cabbage and tomato production in Trinidad, insecticide use was calculated at above 40.0% and 100.0% respectively of recommended rates, despite the introduction of parasitoids for cabbage pest control and reports that fruit‐ and leaf‐feeding tomato pests may not cause serious yield loss. An IPM strategy for these crops is suggested based on increased research, including alternatives to pesticides, improved application technology and pest monitoring, together with a strong extension capability.

Alternatives to Synthetic Chemical Insecticides for Use in Crucifer Crops

ABSTRACT Current public concern about the possible adverse effects of agricultural chemicals on health and the environment has generated interest in reducing chemical inputs in vegetable growing. Crucifers are important vegetable crops in Australia and are subjected to attack by lepidopterous pests especially diamondback moth (Plutella xylostella (L.)) and cabbage white butterfly (Pieris rapae (L.)). Control options for cabbage pests reviewed here include use of natural insecticides (mainly plant-based), physical barriers, biological controi, insect sterilization, intercropping, companion planting and host plant resistance. Successful reduced chemical insect control should concentrate on combining several of these options in complete pest management systems.

Developing an action threshold for lepidopterous pests of cabbage

Developing an action threshold for lepidopterous pests of cabbage

Effect of Formulations of Bacillus Thuringiensis Var. Kurstaki on Lepidopterous Pests of Cabbage, 1989

Abstract Greenhouse-grown seedlings were transplanted on 31 May into plots 4 rows wide by 25 ft long, 15 plants/row, at the University of Illinois Vegetable Crops Farm, Champaign. Plots were replicated 4 times and arranged in a randomized complete block design. Bond adjuvant was used with all treatments except the USDA formulations and Ambush. Sprays were applied with 3 hollowcone nozzles (Teejet TXSS8)/row from a 4-row sprayer delivering 30.8 gal/acre (for USDA treatments = 20.4) at 50 psi. Sprays were applied on 30 Jun and 6, 13, 24, and 31 Jul. Two destructive samples (5 plants/plot) were taken 5 Jul and 27-30 Jul. Field populations of DBM were augmented from a laboratory colony before the first treatment application. Head yields and quality (10 plants/ plot) were determined at harvest. Insect counts were transformed by x + 0.5 for analysis.

Control of Cabbage Pests in South Texas, 1988:

Abstract ‘Early Round Dutch’ cabbage was direct seeded in plots at the Texas Agricultural Experiment Station, Weslaco, Tex., on 19 Feb 1987. Experimental design was a randomized complete block with 4 replicates. Plots were 2 beds wide, 1 row/bed, and 40 ft long. Pest surveys were initiated 21 Mar and were conducted by counting all lepidopterous larvae and aphids on 3 randomly selected plants/plot. Surveys were conducted 6 DAT, and plots were treated 1 d after surveys whenever larval counts averaged greater than 0.3/plant or aphids averaged greater than 10/plant. Insecticide applications were made with a tractor-mounted spray boom with 4 nozzles/bed at 40 psi and a rate of 10 gal/acre until 26 Apr, at which time rates were increased to 20 gal/acre. Plots were rated for damage at head maturity by examining 10 plants/plot and noting the number of heads with insect-feeding damage and the number infested with larvae or aphids. Data from insect surveys were pooled across survey dates and subjected to ANOVA.

Tests of a Spun Polyester Row Cover as a Barrier Against Seedcorn Maggot (Diptera: Anthomyiidae) and Cabbage Pest Infestations

Reemay, a spun polyester row-cover material, was tested as a barrier to insect pest infestations in two different systems. The row cover was ineffective in preventing infestation of seeds by seedcorn maggot, Delia platura (Meigen), suggesting that eggs or larvae were already present in the field at time of planting. The row cover dramatically reduced populations of cabbage insect pests (lepidopterous larvae, flea beetles, cabbage maggots, and aphids) as well as numbers of insect-damaged cabbage heads in both 1984 and 1986. In 1986, numbers of heads produced were lower under the row cover, probably because of bacterial rot due to excessive humidity. Marketable yields were still substantially higher under the row covers.

Composite Action Thresholds for the Control of Lepidopterous Pests on Fresh-market Cabbage in the Lower Rio Grande Valley of Texas

Various decision-making methods for controlling the complex of lepidopterous pests of cabbage, including Spodoptera exigua (Hubner), Trichoplusia ni (Hubner), and Plutella xylostella (L.), were evaluated in the lower Rio Grande Valley of Texas from October 1983 to March 1985. Large-scale tests in commercial cabbage fields demonstrated that an action threshold of 0.3 larvae per plant maintained damage below 1% of total harvested cabbage, similar to damage seen in conventionally scouted fields. On the average, two fewer insecticide applications were required in cabbage fields using the threshold of 0.3 larvae per plant compared with conventionally scouted fields. In small-plot tests, the action threshold of 0.3 larvae per plant and weekly pesticide applications resulted in equal yields. Both methods resulted in greater marketable yield than did either a damage-based threshold of one to three feeding sites per plant or no pesticide applications.

Título en español

Se estudió el ciclo de vida de la alevilla del dorso de diamante, Plutella xylostella (L.), la plaga más dañina del repollo en Puerto Rico. El trabajo incluye la descripción y la duración de todas las etapas del ciclo de vida de este insecto y mediciones de las larvas (largo del cuerpo y ancho de la cápsula cefálica). La duración media de las etapas de huevo, larva, prepupa, pupa y adulto fue 3, 11.7, 1, 3.6 y 11.1 días, respectivamente. La longitud de la larva y el ancho del armazón cefálico en milímetros para la primera, segunda, tercera y cuarta fase larval fueron de 1.2, 2.1, 3.7, 7.0 y 0.15, 0.24, 0.40 y 0.56, respectivamente.

Economic analysis of a promising cultural practice in the control of moth pests of cabbage

Various planting patterns of cabbage and tomato were investigated to assess whether such a cultural practice could fcring about reduction in the incidence of Plutella xylostella (L.) and Crocidolomia binotalis Z. on cabbage. No reduction in the larval incidence of both the pests was observed when different combinations of cabbage and tomato were planted at the same time. A slight reduction in the incidence of both the lepidopterans had ensued in all the planting patterns, when cabbage was planted 15 days later than tomato. Maximum reduction, however, was observed following planting pattern of one row cabbage and one row tomato (cabbage planted 30 days later than tomato). It is further opined that this type of cultural practice cannot be used as a sole control measure for both the pests, since the marketable yield of cabbage recorded in the promising intercrop combination was well below the attainable yield that could be expected when insecticide sprays are undertaken on pure cabbage. Significant reduction in net return was also obtained following this cultural practice as compared to cabbage receiving insecticidal sprays based on different management programmes.

Cabbage Lepidopterous Pests and Their Parasites in Southwestern Virginia

Lepidopterous pests of cabbage and their parasites in southwestern Virginia were investigated in 1981 and 1982 in a pesticide-free plot. The imported cabbageworm, Artogeia rapae (L.) (formerly in Pieris ), peaked in mid-July and was the major pest. The cabbage looper, Trichoplusia ni (Hubner), which peaked in August and June in 1981 and 1982, respectively, was the second most important pest. Small numbers of diamondback moth, Plutella xylostella (L.), were present. A. rapae and T. ni had two to three generations per year. Of 14 parasite species recovered, 3 were common. Parasitization of A. rapae larvae by Cotesia glomeratus (L.) (formerly in Apanteles ) averaged ca. 25% each year. Pteromalus puparum (L.) parasitized 70 and 32% of the A. rapae pupae during 1981 and 1982, respectively. Parasitization of T. ni larvae by Voria ruralis (Fallen) averaged 27% in 1981 and 17%in 1982.

Composite Economic Threshold for Three Lepidopterous Pests of Cabbage

A composite threshold for three lepidopterous cabbage pests, Trichoplusia ni (Hubner), Plutella xylostella (L.), and Pieris rapae (L.), was developed for use in fresh market cabbage. A multiple regression model was developed which describes percent marketable yield as a function of selected variables. The variables were: seasonal mean number of all larvae per plant, percent T. ni larvae > 13 mm in length prior to the plant stage of “cupping,” mean seasonal temperature in °C, and the interactions among these three variables. The threshold was shown to be dynamic, but a static, composite threshold of 0.30 larvae per plant would produce at least an 80% marketable yield. Insecticide treatment schedules based on assessment of larval populations resulted in a reduction of from one to four-and-one-half applications below the number used in a 5- to 6-day automatic schedule, while simultaneously providing the same or higher yields.

Use of Action Thresholds for Management of Lepidopterous Larval Pests of Fresh-Market Cabbage

Management programs involving the use of action thresholds to initiate insecticide treatments for controlling the complex of cabbage-feeding lepidopterous larvae were evaluated in comparison with a standard weekly spray program. Use of thresholds of percent infested plants throughout both cabbage growth stages (preheading and heading) reduced required spray applications by three and by four to seven in spring and summer plantings of cabbage, respectively. There was no significant effect on production of marketable plants compared with cabbage treated weekly from the first appearance of larvae until harvest. Sampling for infested plants required substantially less time than counting larvae per plant. A management program using thresholds of percent infested plants provides a simple, practical means of rapidly assessing and controlling larval populations with the potential for reducing insecticide use.

Polistes Wasps (Hymenoptera: Vespidae) as Control Agents for Lepidopterous Cabbage Pests

We obtained a significant gain of weight and quality of cabbage in plots exposed to foraging Polistes wasps compared with cabbage in control plots. This reflects the significant reduction in numbers of large Pieris rapae larvae due to wasp predation. In 1980 the reduction in larvae did not show a corresponding reduction in damage and loss of yield. One average nest of wasps (5.6 wasps) was sufficient to reduce Pieris populations by up to five larvae (44%) on each of ca. 20 cabbage plants during the season. A major reason levels of control achieved by Polistes in this study were not higher was the availability of alternate prey.

Evaluation of Insecticide Usage in the New York Processing-Cabbage Pest Management Program1

Insecticide usage in the Cornell University Processing (sauerkraut) Cabbage Pest Management Pilot Program was evaluated over the 4-year period from 1978 to 1981. Insecticide load was assessed in terms of dose equivalents. Insecticide efficacy was measured by percent reduction of Lepidoptera and percent reduction of plants infested with onion thrips, Thrips labaci Lindeman. Total insecticide load, in average dose equivalents per field, decreased every year from 1978 to 1980, but increased in 1981. The increase in dose equivalents in 1981 was due to multiple applications of insecticides by growers to suppress high populations of thrips. However, during the 4-year period, most insecticides were applied to control Lepidoptera, and comparing 1981 with 1978, the amount of insecticides used against Lepidoptera decreased by 49%, whereas their effectiveness increased by 54%. These results are attributed to better insecticide selection and improved timing of applications due to development of action thresholds used in conjunction with weekly field scouting. Methamidophos and the pyrethroids consistently provided the most effective control of Lepidoptera. Control of thrips by foliar insecticides was inadequate for present Food and Drug Administration standards.

Variable-Intensity Sampling: A New Technique for Decision Making in Cabbage Pest Management1

A variable-intensity sampling method was developed to efficiently monitor all cabbage pests in commercial fields in New York while concentrating on the most important pests, Pieris rapae (L.) and Trichoplusia ni (Hubner). The field is walked in a V-shaped pattern which is divided into 10 segments. Along each segment, one to four randomly selected cabbage plants are inspected, the number depending on an estimate of population density of P. rapae and T. ni derived from previous segments. Computer simulations of this procedure were run, using random numbers from the appropriate negative binomial distribution, and the 95% confidence intervals calculated contained the true mean with frequencies between 93 and 97%. In a commercial cabbage field, a comparison of estimates of the means obtained by variable intensity sampling and fixed sample sizes of 40 and 264 plants revealed only small differences.

Onion thrips (Thysanoptera: Thripidae) damage and contamination in sauerkraut.

Studies conducted to determine Thrips tabaci Lindeman damage and contamination in sauerkraut revealed that both occur at detectable levels in processed cabbage, although such levels are much lower than predicted from examination of fresh cabbage. Addition of the chemical preservatives sodium benzoate (0.1%) and potassium metabisulfite (0.05%) had no effect on plant tissue damage or insect contamination. Although tolerance levels for insect contamination in many other vegetables have been established, the FDA has not established such a tolerance for insect contaminants in sauerkraut. To avoid discretionary seizure, and in light to these findings on this newly important pest of cabbage, guidelines should be established for plant injury and insect tolerances.

Photoelectrically-Operated Intermittent Sprayers for the Insecticidal Control of Horticultural Insect Pests12

Automatic intermittent sprayers, using pulse-modulated, IR sensors to detect plants and trigger insecticidal sprays, controlled insect pests of cabbage, cauliflower, and peppers during 1978–79 as well as a continuous sprayer did. Reductions in the usage of pesticides ranged from 24–51% depending upon the crop and the mode of operation of the intermittent sprayer.

THE EFFECT OF COMPANIONATE PLANTING ON LEPIDOPTERAN PESTS OF CABBAGE

Companionate planting is one of many insect control strategies propounded by organic growers. A variety of herbs are purported to possess repellent properties to many insect pests of vegetables (Rodale 1975; Yepsen 1976; Hill 1976; Anonymous 1977a). According to Atsatt and O'Dowd (1976), repellent plants are members of plant defense guilds which prevent herbivores from locating their hosts. Perrin and Phillips (1978) reviewed the elements of natural pest control characteristic of mixed cropping systems and outlined suggestions for transferring these elements to “agronomically acceptable” monocultures. However, very little work has been done to substantiate these claims and field evidence of the protective properties of companionate plants is, therefore, warranted. This becomes all the more important because of the dramatic increase in home gardening recently in North America. It is estimated that 33 million home and community gardens were grown in the United States during 1976 and 1977 (Anonymous 1977b). Here we describe the results of field experiments in which we sought to quantify the effect of companionate plants against major lepidopteran pests of cabbage in southside Virginia.