Cabbage Fields Research Articles

コナガのほ場密度の季節的消長と寄生蜂の活動

コナガのほ場密度の季節的消長と寄生蜂の活動

Evaluation of Biological Insecticides for Control of DBM, 1990

Abstract A small plot field study was conducted in a commercial cabbage field near Alamo, Tex. to evaluate various Bacillus thuringiensis formulations for control of DBM on cabbage. Experimental plots measuring 2 rows (one 40 inch bed) by 20 ft were established on 26 Jan. Plots were sprayed using a CO2 pressurized backpack sprayer with a total volume of 50 gal of spray/ acre (2 10 × hollow cone nozzles/bed; 50 psi). Treatments were applied on 26 Jan and 2, 8, 15 and 22 Feb. On the last 2 spray dates, a surfactant (Leaf Act 80; 8 oz/100 gal) was added to all treatments. Larval populations were monitored in each plot by counting the total number of larvae on 3 plants on 1, 7 and 14 Feb, and by counting the total number of larvae on 5 plants on 20 and 26 Feb. The experimental design was a randomized complete block with 4 replications.

Evaluation of Biological and Synthetic Insecticide Combinations for Control of Dbm, 1990

Abstract A small plot field study was conducted to evaluate various Bacillus thuringiensis (Bt) products alone and in combination with synthetic insecticides for control of DBM on cabbage. Experimental plots were established in a commercial cabbage field near Donna, Tex. Each plot was 2 rows wide (one 40 inch bed) by 15 ft long. Treatments were applied using a CO2 pressurized backpack sprayer in 50 gal of spray/acre (2 10 × hollow cone nozzles per bed; 50 psi). All treatments included a spray adjuvant (LI700 at 8 oz/100 gal). Two applications were made 4 d apart (19 and 23 Feb) with treatment evaluations performed 4 days after each treatment. Treatments were evaluated by visually counting all DBM larvae on 5 plants/plot. The experimental design was a randomized complete block design with four replications.

The influence of seed quality and pregermination treatment on cauliflower and cabbage transplant production and field growth

SummarySeedling emergence and subsequent growth from untreated seeds and selected‐germinated seeds which had been dried before sowing (low‐moisture‐content germinated (LMCG) seeds) were compared in cellular trays in a glasshouse and in the field following transplanting. Three seed lots of different quality of the same cultivar were used for cabbage and cauliflower. In all cases, seedling emergence was greater, earlier and more uniform from LMCG seed than that from untreated seeds. LMCG seed effectively eliminated the differences due to seed quality shown by untreated seeds at emergence suggesting an improvement in seed vigour as well as viability from the selection treatment. Higher quality seed and LMCG cauliflower seed led to larger curd weights and therefore an increase in marketable yield at harvest compared to that from lower quality seeds. However, differences in transplant uniformity due to seed quality and seed treatment had little impact of agronomic significance following transplanting.

Studies ontrichogramma buesi as a biocontrol agent againstPieris rapae in Egypt

Trichogramma buesi was reared in the laboratory on eggs of the Mediterranean flour moth,Anagasta kuehniella. The incubation period of the parasite's egg was 27 h at 23 °C and 22 h at 27 °C. The larval stage lasted 3.6 and 3.2 days, the pre-pupa lasted 16 and 23 h, and the pupa lasted 5.4 and 4.6 days at 23° and 27°C, respectively. The total developmental time (from egg to adult) averaged 9.2, 9.4, and 9.1 days when the parasite was reared on eggs ofPieris rapae, Spodoptera littoralis, andA. kuehniella, respectively, at 27 °C. Sex ratio inT. buesi was 1 ♂: 1 ♀ in nature and 1 ♂: 1.3 ♀ in the laboratory. The daily and total numbers or progeny produced/female were 5.1 and 98.2 adults, respectively. The parasite female, fed on honey, lived 10.7 days at 27 °C and 12.1 days at 23 °C. Percentages of parasitism byT. buesi on eggs ofP. rapae collected from cabbage fields ranged between 0 and 31.5 % in 1985 and betwcen 0 and 36.4% in 1986 during July through December. The respective figures on eggs collected from turnip fields were 16–42.2% and 12.5–32.1% during November and December.

Studies on Apanteles litae var. operculellae, a Parasite of the Diamond‐back Moth, Plutella xylostella in Egypt

AbstractApanteles litae var. operculellae was reared in the laboratory on 2nd instar larvae of Plutella xylostella. The incubation period of the egg was 44 hours at 25 °C and 26 hours at 30°C. The larval stage (3 instars) lasted 6.7 and 5.6 days, the pre‐pupa lasted 24 and 15 hours, the pupa lasted 4.7 and 3.8 days at 25° and 30°C, respectively. The total developmental period of the parasite (from egg to adult) was 14.5 days at 25°C and 11.1 days at 30°C. Sex ratio in A. litae var. operculellae was found to be 1 ♂: 0,83 ♀ in nature and 1 ♂: 0.80 ♀ in the laboratory. Adult females, fed on honey, lived an average of 15.9 and 11.6 days at 25° and 30°C, respectively. The respective figures for males were 14.6 and 6.2 days. – Percentages of parasitism by A. litae var. operculellae in P. xylostella larvae collected from cabbage fields ranged between 0 and 13.7 in Kalubyia Governorate (during May 1981–May 1982) and between 0 and 9.8 in Fayioum Governorate (during July–December 1982).

Patterns of parasitism by Trybliographa rapae, a cynipid parasitoid of the cabbage root fly, under laboratory and field conditions

ABSTRACT. The spatial patterns of parasitism of the cabbage root fly caused by the cynipid parasitoid Trybliographa rapae (Westw.) have been studied in a laboratory system, within field cages and in a natural situation. Continuous observations during the laboratory experiments showed the parasitoids to spend proportionately more time on the patches of high host density. This resulted in the per cent parasitism per patch being directly density dependent. Similar patterns of parasitism were found from the field cage system, and also from experiments using the natural parasitoid population and either manipulated or natural host densities. While mutual interference was marked in the laboratory experiments, there was little or no sign of it within the larger field cages.

Influence of Container Type and Cell Size on Cabbage Transplant Development and Field Performance

Abstract Greenhouse and field studies were conducted to determine the influence of container type and cell size on cabbage [Brassica oleracea (L.) Capitata Group] transplant growth and subsequent yield. Cabbage seedlings were grown in the greenhouse in two types of containers, Sutton polystyrene and Speedling styrofoam “Todd Trays”. Four sizes of each tray were tested, ranging from 8.0 to 80.5 cm3 for polystyrene and 7.5 to 80 cm3 for styrofoam. In general, stem diameter, plant height, and leaf area of seedlings increased with increase in container size, but container type had no influence. In the field, head width and length were similar for all treatments. Plants grown from the large cell sizes had higher head weight than those from small cell sizes.

Biological and ecological studies onDiadegma semiclausum Hellen (Hym., Ichneumonidae), a larval parasite of the Diamond-Back Moth,Plutella xylostella (L.) (Lep., Plutellidae) in Egypt

Diadegma semiclausum was reared in the laboratory on 2nd and 3rd instar larvae ofPlutella xylostella. At 25°C, the incubation period of the parasite's egg was 38h; the following stages lasted 5.4 days (5 instars), 33h (pre-pupa), and 5.9 days (pupa). Superparasitism occurred but only one parasite developed from one host larva. Sex ratio inD. semiclausum was found to be 1∶1 in nature as well as in laboratory. The daily and total rate of eggs deposited per female were 13.6 and 164.2, respectively. The parasite male and female, fed on honey, lived for 11.2 and 14.6 days, respectively. Laboratory trials failed to rearD. semiclausum on certain lepidopterous larvae other thanP. xylostella. Percentages of parasitism byD. semiclausum inP. xylostella larvae collected from cabbage fields during 1982 ranged between 0 and 66%.

Marking Adult Diamondback Moth, Plutella xylostella (L.), and Estimation of Adult Survival Rate and Population Density in a Cabbage Field

Nine non-commercial colored aerosol dyes were screened in the laboratory to determine their suitability for marking the adults of Plutella xylostella in the field. The satisfactory dyes were Solar Pure Blue, Acid B. M. Green, Solar R. B. and Acid Scarlet B. A. These dye marks were easily recognized on the moths. None of the dyes tested did not affect the longevity of the moths and the dyes remained better on the body than on the wings when water was applied. Solar Pure Blue and Solar R. B. marked moths did not differ significantly from unmarked moths in longevity, fertility and the number of mating pairs. A method of marking P. xylostella adults in the field was described. The survival rate of moths in a summer cabbage plot, estimated using JACKSON'S (1939) 'positive method' was 0.67 per day.

Control of Imported Cabbageworm and Cabbage Looper Using Pyrethrin, Rotenone, or Asana with or Without One of Four “Synergists,” 1987

Abstract The experiment was located in a commercial transplanted cabbage field near Belle Plaine, Minn. Plots were two 38 inch rows, 25 ft long, replicated 4 times, and arranged in a randomized complete block. Insecticide applications were made on 28 Jul with a handheld CO2 sprayer using 40 psi pressure and 17 gal total material/acre. Temperature at application was 90°F. Numbers of living and dead larvae were counted on 5 plants 24 h posttreatment in reps 1 to 3 and 48 h posttreatment in rep 4. Larval counts were converted to % control, transformed using ARCSINE, and the means were compared. Phytotoxicity was observed particularly due to Rotacide earlier, so a l-to-3 scale was used, with the most intense purple and brown cabbage discolorations considered a 3.

Comparative Efficacy of Several Pyrethroids and Dosages Against Cabbageworm and Cabbage Looper, 1987

Abstract The trial was located in a commercial transplanted cabbage field near Belle Plaine, Minn. Plots were 2 rows, 25 ft long arranged in a randomized complete jlock design, and replicated 3 times. Insecticide applications were made on 26 Jul with a hand-held COa sprayer using 40 psi pressure and 17 gal total material/acre. Temperature at application was 90°F. Numbers of living and dead larvae were counted on 5 plants 24 h posttreatment. Larval counts were oonverted to % control, transformed using ARCSINE, and means were compared.

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.

Mating suppression effect on the diamondback moth by their synthetic sex pheromone in the cabbage field

Mating suppression effect on the diamondback moth by their synthetic sex pheromone in the cabbage field

Parasitism and Utilization of Imported Cabbageworm Pupae by Pteromalus puparum (Hymenoptera: Pteromalidae)

Pteromalus puparum (L.) parasitized 64.1 and 32.5% of imported cabbageworm, Artogeia rapae (L.), pupae collected from pesticide-free cabbage field plots in 1983 and 1984, respectively, in southwestern Virginia. Parasitism was most pronounced in the latter part of the season. In commercial cabbage fields, 67.2% of overwintering pupae were parasitized. High percentages of parasites successfully emerged as adults, indicating efficient host utilization. Most parasite mortality within the host occurred in the larval stage; mean adult parasite emergence per host for 1983 and 1984 was 52.3, with a 1:1 sex ratio. However, variability of male parasites per host was double that of females. Females weighed twice as much as males, suggesting a compensation of number for size. P. puparum did not parasitize either host sex discriminately, and equal numbers of male and female parasites emerged from both host sexes. Laboratory studies suggest that host/parasite ratios and length of host/parasite exposure time are important considerations for laboratory rearing of P. puparum . Suboptimal conditions result in unparasitized and mutilated hosts.

The development and comparison of visual damage thresholds for the chemical control of Plutella xylostella and Crocidolomia binotalis on Cabbage in India

An economic threshold on fresh cabbage affected by Plutella xylostella (L.) and Crocidolomia binotalis Z., based on visual estimates of defoliation and a determination of this damage on the marketable yield was developed. An initial survey of unprotected cabbage field for determination of general levels of number of holes caused by feeding of both the lepidopterous pests formed a prerequisite for conducting visual damage threshold experiments. Maintaining a low visual damage threshold of up to 1.0 mean hole (mean of two leaves) on the wrapper leaves, after initial protection of primordia, was found to be an effective alternative in reducing present reliance on weekly or fortnightly sprays for the control of both the pests on cabbage. The possibility of eliminating precupping sprays is supported by the study since the larval populations causing damage to either outer leaves or leaves about to cover the head did not reduce the yield to a significant extent. The use of thresholds based on larval counts of either P. xylostella or C. binotalis failed to give enough lead time during scouting and resulted in loss of marketability.

Ecology of Thysanoptera within Cabbage Fields

The occurrence and species composition of thrips within cabbage fields were studied during 1981 and 1982. Temporal differences in abundance and species composition depended on the spatial relationship of cabbage fields to cereal and forage crops. Sticky traps within cabbage fields recorded peak flights of thrips during maturation and senescence of adjacent wheat or oat fields and cutting of adjacent alfalfa and red clover fields. These data indicate several important findings regarding the ecology of thrips in general and the possible management of Thrips tabaci Lindeman in particular. First, although there are large numbers of thrips in cabbage fields during certain time periods (e.g., maturation or harvesting of crops), most will not be T. tabaci and need not be of concern to cabbage growers. Second, there are significant differences in thrips phenology and species composition in cabbage fields, and these differences appear to be dependent on phenology and management of adjacent field and forage crops. Third, although many other species are present, T. tabaci appears to be present in adequate numbers to infest cabbage at the critical period of head formation. This critical period occurs at different times depending on area, planting date, variety, and weather.

Species Composition and Phenology of Thysanoptera within Field Crops Adjacent to Cabbage Fields

Studies were conducted in 1981 and 1982 to determine the general temporal occurrence of thrips in wheat, alfalfa, oat, and red clover fields adjacent to cabbage fields in upstate New York. Shifts in species composition of thrips on these crops were observed through time, and fluctuations in abundance were attributed to changes in habitat structure (e.g., maturation and senescence in wheat and oats, and cropping practices in alfalfa and red clover). All of these crops serve as a reservoir for Thrips tabaci Lindeman, which may move to and infest nearby cabbage plantings. By sampling the thrips populations within the foliage and utilizing sticky traps to monitor aerial populations, we may be able to predict the population buildup within these crops and the subsequent movement of thrips to adjacent crops.

Carabid species and activity densities in biologically and conventionally managed cabbage fields

AbstractCarabid beetles were sampled using pitfall traps on 3 biologically and 4 conventionally managed cabbage fields near Frankfurt, FRG, during 2 growing seasons. The total carabid catch was 4541 individuals representing 54 species. Of the 10 most abundant species Pterostichus melanarius, P. cupreus, Loricera pilicornis, and Agonum dorsale were significantly more abundant in biologically managed fields, whereas Trechus quadristriatus, Bembidion quadrimaculatum, and B. lampros were more abundant in conventionally managed fields. The total biomass of captured carabid beetles was in biologically managed fields significantly higher (about 2–20 times) than in conventionally managed fields throughout the summer. The higher carabid activity density in biologically managed fields was probably due to the more abundant soil fauna and other sources of prey. More carabid species were found on biologically than in conventionally managed fields, but no significant difference in the species diversity index was detectable. Based on dominance similarity comparisons between the studied fields, the method of farming seemed to modify annually the carabid fauna to be indicative of the practiced farming method.ZusammenfassungLaufkäferarten und ihre Aktivitätsdichte auf biologisch und konventionell bewirtschafteten KohlfeldernWährend 2 Anbauperioden wurde die Laufkäferfauna auf 3 biologisch und 4 konventionell bewirtschafteten Weißkohlfeldern in der Nähe von Frankfurt am Main, BRD, mit Hilfe von Pitfallfallen untersucht. Die Gesamtzahl der gefangenen Individuen betrug 4541, die 54 verschiedene Arten repräsentierten. Von den 10 am häufigsten aufgetretenen Arten waren Pterostichus melanarius, P. cupreus, Loricera pilicornis und Agonum dorsale signifikant zahlreicher auf biologisch bewirtschafteten Feldern, wohingegen Trechus quadristrichatus, Bembidion quadrimaculatum und B. lampros signifikant häufiger auf konventionell betriebenen Feldern vorkamen. Auf biologisch bewirtschafteten Feldern lag die Gesamtbiomasse der Laufkäfer ebenfalls signifikant höher (2–20mal) als auf konventionell bewirtschafteten Feldern. Die höhere Laufkäferaktivitätsdichte auf biologisch bewirtschafteten Feldern dürfte auf die vielfältigere Bodenfauna und auf andere weitere Nahrungsquellen zurückzuführen sein. Obwohl ein größerer Artenreichtum auf biologisch betriebenen Feldern als auf konventionell bewirtschafteten festgestellt wurde, konnte kein signifikanter Unterschied im Artendiversitätsindex nachgewiesen werden. Dominanzsimilari‐tätsvergleiche zwischen den Untersuchungsfeldern deuten darauf hin, daß die Laufkäferfauna jährlich von der Bewirtschaftungsmethode charakteristisch modifiziert wird.

Inhibition of flowering in Chinese cabbage by applying heat and growth retardants to transplants

A procedure was developed to reduce premature bolting and flowering in Chinese cabbage grown in the field during the winter. This involved (a) the use of geothermic water as an inexpensive heat source for heating the transplants in the nursery; (b) application of the growth retardants daminozide (Alar) and paclobutrazol (PP333) to the heated plants before removing them to the field; and (c) application of daminozide to the plants in the field. This procedure markedly reduced stem elongation and the length of the internal stem in relation to the head without affecting the size of the head. Furthermore, application of daminozide in the field minimized the severity of tipburn, a common physiological disorder in Chinese cabbage fields. The result of such treatment was the production of high-quality Chinese cabbage heads which otherwise are unobtainable during the winter.