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Small grains are interseeded with several vegetable crops in Michigan to protect them from wind and water erosion. When the vegetable crop is well-established, the small grain is killed with a graminicide. Research was conducted to determine the optimum combination of small grain species, age of kill, and nitrogen application rate for acceptable pickling cucumber yield in a single harvest. In several experiments, barley, oats, rye, and wheat were seeded at 130 seeds/m2 in the field. Cucumbers were seeded 1 week later. The cover crops were treated with sethoxydim at 0.21 or 0.31 kg·ha–1 plus 1.25% COC when they were 7 to 10 or 13 to 16 cm tall. Small grain size at application had no effect on their kill with sethoxydim or on cucumber yields. Barley and rye were the most vigorous small grains up to 3 weeks after seeding, but oats were similar in size by 4 weeks. Wheat was slower to develop, and more difficult to kill with sethoxydim. The optimum nitrogen treatment was 34 kg·ha–1 before planting the cover crop, followed by 45 kg·ha–1 at the two- to three-leaf stage of cucumber.
Cucumber is an important vegetable in Michigan, where it is grown for slicing (fresh) or processing. Michigan is the top producer of pickling cucumbers in the United States, with over 27% of the total national production. Studies were conducted in 2004 to test the effects of plant density on cucumber fruit quality. Cucumber var. `Vlaspik' was seeded in 30.5, 45.7, 61.0, and 76.2 cm rows with 12.7 cm spacing between plants inside the row, corresponding to final plant populations of 258, 172, 129, and 103 thousand plants/ha, respectively. The experiment used a randomized complete-block design with 4 replications and four rows per plot. At harvest, 10 fruits of grade 2 were randomly selected from each plot for measurement of specific gravity, firmness, soluble solids, color, and seed size. Cucumber fruit specific gravity, soluble solids, and seed size were not affected by plant population size. However, fruit firmness and color varied with plant density. Low plant populations, when compared to high populations, produced darker green fruits, a desired trait in pickling cucumber production. On a scale of 0 (yellowish) to 5 (dark green), plants grown under a population of 258 thousand plants/ha scored an average of 2.8. The score was 4.6 for fruits produced in plots with 103 thousand plants/ha. Low plant populations increased fruit firmness as measured by a puncture test. Fruit firmness was 89, 93, 97, and 95 g·mm-2 for 258, 172, 129, and 103 thousand plants/ha, respectively. Results suggest that cultural practices may affect pickling cucumber fruit quality.
Pickling cucumbers (Cucumis sativus L.) for machine harvest were interplanted with barley (Hordeum vulgare L.), oat (Avena sativa L.), rye (Secale cereale L.), sorghum-sudan (Sorghum vulgare L.), or wheat (Triticum aestivum L.). Cover crops 3 to 5 (7.6 to 12.7 cm) or 6 to 10 inches (15.2 to 25.4 cm) tall were killed with sethoxydim. Cover crops seeded at ≈12 seeds/ft2 (129 seeds/m2) provided protection from wind erosion and minimal crop competition. Additional nitrogen to obtain maximum yield was required when small grain cover crops were interplanted with cucumbers. Barley emerged rapidly, grew upright, and was killed easily with sethoxydim, making it ideal for interplanting. All cover crops caused some cucumber yield reduction under adverse growing conditions.
An evaluation of the effect of bed width (24, 28, 32, and 36 inches) on the control of a mixed population of nutsedge [yellow nutsedge (Cyperus esculentus) and purple nutsedge (C. rotundus)] was conducted with an emulsifiable concentrate formulation of a 1,3-dichloropropene (1,3-D) and chloropicrin (CP) mixture (1,3-DCP) for application through drip irrigation systems. Beds were mulched with either 1.4-mil-thick virtually impermeable film (VIF) or 0.75-mil-thick high-density polyethylene (HDPE) and 1,3-DCP was applied at 35 gal/acre by surface chemigation or via subsurface chemigation 6 inches deep within the bed. HDPE was more permeable to gaseous 1,3-D than VIF so that 1 day after treatment (DAT), 1,3-D gas concentration at the bed centers under VIF was significantly higher than under HDPE. Dissipation of 1,3-D gas with HDPE occurred within 7 DAT, but dissipation with VIF took ∼10 days. In bed centers, 1,3-D concentrations 1 DAT were in the range of 2.3 to 2.9 mg·L–1 whereas in bed shoulders concentrations ranged from 0.1 to 0.55 mg·L–1. In 2002 and 2003, 1,3-D concentration in shoulders of narrower beds was significantly higher than in the wider beds, but dissipated more rapidly than in wider beds. Lower initial 1,3-D concentrations were observed with HDPE film in shoulders than with VIF and the rate of dissipation was lower with VIF. At 14 DAT, nutsedge plants were densely distributed along bed shoulders (19 to 27 plants/m2) with little or no emergence in the centers of beds (fewer than 5 plants/m2), but with no response to bed width. Nutsedge density increased with time, but the nature of the increase differed with bed width. The most effective nutsedge suppression was achieved with 36-inch beds, which had densities of 11–13 plants/m2 on bed centers and 53 plants/m2 on bed shoulders by 90 DAT. Nutsedge suppression was initially more effective with VIF than with HDPE film, so that no nutsedge emerged in the centers of beds mulched with VIF compared with 2–7 plants/ m2 with HDPE by 14 DAT. On bed shoulders there were 2–7 plants/m2 with VIF and 32–57 plants/m2 with HDPE. Increase in nutsedge density with time was greater with VIF so that by 90 DAT nutsedge densities on bed centers and shoulders were greater than with HDPE in 2002 and the same as with HDPE in 2003. Subsurface chemigation did not consistently improve suppression of nutsedge when compared with surface chemigation. Concentrations of 1,3-D in bed shoulders irrespective of bed width were nonlethal. Initial superior nutsedge suppression with VIF did not persist. Nutsedge control in a sandy soil with 1,3-DCP chemigation is unsatisfactory with one drip-tape per bed.
Members of the American Association of Nurserymen and the Society of American Florists were surveyed as to their use of herbicides and nonchemical alternative weed control practices for 1993. Glyphosate was the top-ranking herbicide among the total of 37 reported, in terms of number of respondents and estimated total amounts of active ingredients applied. It was used by all but two of the respondents that used herbicides in their operations. Oryzalin was the top-ranked preemergent herbicide, and was second only to glyphosate in number of respondents and amount of active ingredient applied. The highest estimated use in amounts of active ingredient applied was in the southeastern (43% of total) and north-central (27% of total) regions, nearly two to three times the estimated use in the northeastern or western regions. However, there were only about 50% more respondents in the southeastern or north-central regions compared to the other regions. About 56% of herbicide active ingredients used were in field sites, 22% in container sites, 19% in perimeter areas, and 3% in green-houses. Large firms (annual sales more than $2,000,000) used the greatest estimated total amount of active ingredients, while small firms (annual sales more than or equal to $500,000) tended to use nonchemical alternatives the most. Nearly all respondents used handweeding or hoeing as part of their weed control program. Mowing was used by 84% of the respondents, 71% used tractor cultivation, and 66% used mulches (includes gravel and black plastic). Alternative methods were rated as somewhat effective to very effective by 65% or more of the respondents who used them.
Growers in the American Association of Nurserymen and the Society of American Florists were queried as to their use of plant growth regulators (PGRs) and nonchemical alternative practices during 1993. Daminozide (B-Nine SP) and chlormequat chloride (Cycocel) accounted for 78% of the total pounds active ingredient and were used by 20% and 17% of the respondents, respectively. In contrast, the rooting compounds indolebutyric acid (Dip `N Grow, Rootone, and Hormoroot) and naphthaleneacetic acid (Dip `N Grow, and Hormodin I, II, and III) were used by 53% and 24% of the respondents, respectively, but combined accounted for less than 3% of total pounds active ingredient. Pruning/pinching was used by the greatest number of respondents (82%) and was the only alternative to PGRs rated as very effective by more than 60% of the respondents. Use of chemical PGRs and nonchemical alternative practices was influenced by region and firm size. In the northeastern United States, growers reported relatively low use of PGRs (frequency and total pounds) and the lowest use of mechanical brushing as an alternative practice. In contrast, mechanical brushing was used most in the western United States. Large firms (more than $2 million in annual sales) reported the greatest use of chemical and nonchemical means of regulating growth.
A national survey of the greenhouse and nursery industry provided data on insecticide/miticide use in 1993. Respondents reported using 46 different compounds, and the industry used an estimated 2.8 million pounds of active ingredients to control insect and mite pests. The most frequently used material was acephate: 52% of the respondents reporting use in 1993. The most heavily used material was a miticide, dienochlor, with an estimated 643,281 lb (292,400 kg) applied, or 28% of the total. Only three other compounds represented more than 5% of the total use—carbaryl (498,073 lb or 22%) (226,397 kg), diazinon (326,131 lb or 14%) (148,242 kg), and propargite (143,888 lb or 6%) (65,404 kg). Of the top four products, two (dienochlor and propargite) are miticides. Together these represented 34% of the total estimated insecticide/miticide use, demonstrating the importance of mites as pests in the industry.
A national survey of the commercial ornamental industry was conducted to determine the current status of pest control including chemical and nonchemical disease control practices. The fungicides thiophanate methyl, chlorothalonil, mancozeb, and metalaxyl were used in the greatest quantity and by the largest percentage of growers. Metalaxyl was used in greenhouse and field operations by the highest percentage of growers, primarily to control root diseases but many growers reported using metalaxyl to control foliar disease. Overall, more fungicides were used in the field for foliar diseases, whereas almost equal amounts of fungicides were used for foliar and root diseases in the greenhouse.
A national survey of the greenhouse and nursery industries was conducted to determine the current status of pest management practices. This study covers the trends in chemical and nonchemical pest control measures and factors that affect adoption of nonchemical control measures. For the 5-year period 1988-93, there appeared to be a decrease in chemical use for disease and insect control and for plant growth regulators. During the same period there was an increase in chemical weed control. The adoption of nonchemical pest control measures was concentrated in the area of insect control. The primary factors limiting use of nonchemical pest control measures were 1) availability of effective materials/biological agents, 2)availability of information, and 3) management complexity. The primary information sources on nonchemical pest control used by growers varied by size of firm and region of the country. For all respondents the primary sources were 1) industry trade journals, 2) other growers in the industry, 3) cooperative extension service, and 4) industry-sponsored seminars.