Throughout the world, growers of horticultural crops employ a multitude of crop and pest management practices designed to reduce pests and minimize crop losses. Although weeds continue to afflict humans (65), host other pests (14), and cause appalling crop losses on a worldwide scale (66, 109, 110), certain weedy species may complement horticultural cropping systems. This paper reviews entomological, pathological, and crop-related literature where manipulation of a specific weed, a weed control practice, or a cropping system can suppress a crop pest. Perhaps horticulturists and colleagues will recognize an opportunity to improve our understanding and our ability to successfully manage one or more of the following examples, thereby improving production efficiencies within modern horticultural cropping systems.
Natural-light growth chambers constructed within a greenhouse compartment were equipped with a ventilation/circulation system, two stages of heating, and evaporative cooling. Air drawn from the greenhouse compartment continuously ventilated the chambers; the air was heated or cooled to the set-point temperature. A computer-controlled environmental system maintained uniform temperatures within the chambers and maintained the temperature within ±1C of the set point at night and during periods of low solar radiation; during higher solar radiation periods, control was not as precise. Carbon dioxide concentration was accurately maintained, and the photosynthetic photon flux from supplemental high-pressure sodium lamps was ≈200 μmol·m-2·s-1. The natural-light growth chambers provide a means for studying the interactive effects of temperature, light, and other environmental variables in experiments to increase production efficiency.
A planting of ‘Starkrimson Delicious’ (Bisbee strain) apple trees was established in 1981 on M.27 EMLA, P.2/KA313, P.22/KA313, and C.6/KA313. After 6 years, trees on P.2/KA313 and C.6/KA313 were similar in size and larger than those on M.27 EMLA and P.22/KA313. P.22/KA313 induced profuse suckering, whereas trees on M.27 EMLA were virtually sucker-free. Cumulative yields per tree (1984–86) were the highest on P.2/KA313 and C.6/KA313. However, cumulative production efficiencies were highest for trees on M.27 EMLA and P.2/KA313. The least efficient trees were on P.22/KA313. Foliar analyses indicated that trees on M.27 EMLA had the highest levels of N, Ca, Mn, and Zn.
This LISA project involves four state universities and the USDA, and has the objective of developing and evaluating non-conventional production and pest management strategies for raspberries and strawberries. Production goals are divided between cropping systems and pest management. The evaluation of trellising systems for cropping efficiency, ease of harvest, and spray distribution is an example of a production related objective. Groundcover management systems for strawberries are being evaluated for their effects on both the pest complex and production system. Biological control strategies for root diseases are also being studied. Evaluations involve field performance, economics, and impacts on pesticide use. In addition, grower attitudes towards adoption of non-traditional production practices have been assessed. The project supports the publication of a newsletter that is distributed to 450 growers. The major goal of our work has been to improve production efficiency and provide growers with economical, dependable tools that can be used to prevent pest problems before chemical intervention is required.
The preservation/restoration of prairie ecosystems is part of our responsibility as stewards of the earth. Success in reestablishing prairie plant communities has been quite variable and far from optimum. This cooperative project between the University of Wisconsin-River Falls (UWRF) and Carpenter Nature Center examine the use of horticulture plug technology as a means of improving the quality, availability, production efficiency and transplant survivability of herbaceous frob prairie species for use in prairie restoration efforts.
Data on growth rates and winter survival of bare-root seedlings and plug seedlings of Rudbeckia hirta, Ratibida pinnata and Zizea aurea in prairie test plots will be presented. The plug seedlings were stockier plants, had well developed root systems, and demonstrated excellent performance as transplants in prairie restoration efforts.
The performance of ‘Marsh’ grapefruit (Citrus paradisi Macf.) and ‘Valencia’ sweet orange [C. sinensis (L.) Osb.] on 18 rootstocks was evaluated with trees spaced 3.1 × 4.6 m and planted in 1968 in a deep, sandy soil. Rootstocks had significant effects on tree size, yield, production efficiency (kg of fruit/m3 of canopy), fruit quality and the quantity of soluble solids/tree. The largest, most productive trees were generally those on rough lemon (C. jambhiri Lush.) in contrast to the smallest trees on the hybrid C. sunki Hort. ex Tanaka × Swingle trifoliate orange (Poncirus trifoliata Raf.). Rootstocks that showed promise for use in close-spaced plantings were Rubidoux trifoliate orange, Rusk citrange (P. trifoliata × C. sinensis) Koethen sweet orange × Rubidoux, Rangpur lime (C. limonia Osb.) × Troyer citrange, and a mandarin.
A planting was established in 1964 and 1965 to evaluate the following ‘Delicious’ strains: ‘Red Prince’, ‘Jardine Red’, ‘Royal Red’, ‘Turner Red’, ‘Richared’, ‘Rogers Red’, ‘Gardner Red’, ‘Sturdeespur’, and ‘Starkrimson’, the last 2 being spur types. The strains have been evaluated through 1979. Leaf N, K, Ca and Mg levels varied among the strains but none was consistently different from another. The cumulative yield per tree from 1970 to 1979 was higher for all standard strains except ‘Red Prince’ than for the spur strains. Theoretical cumulative yield per hectare was highest for ‘Sturdeespur’ and significantly higher than all other cultivars with the exception of ‘Turner Red’. ‘Sturdeespur’ had the highest production efficiency. Watercore severity at harvest was inconsistent among the strains, but in 3 of 4 years fewer ‘Starkrimson’ fruits were affected.
NASA has investigated the use of recirculating nutrient film technique (NFT) systems to grow higher plants on long-duration space missions for many years and has demonstrated the feasibility of using recirculating systems on numerous crop species. A long duration (418-day) experiment was conducted at Kennedy Space Center, Fla., to evaluate the feasibility of using recirculating hydroponics for the continuous production of Solanum tuberosum L. `Norland'. The productivity of four sequential batch plantings was compared to staggered harvest and plantings. The accumulation of bioactive organic compounds in the nutrient solution resulted in reduced plant height, induced early tuber formation, and increased harvest index of the crops in both production systems. The changes in crop development were managed by increasing planting density and reducing cycle time to sustain production efficiency.
A 1995 study of 22 Australian nurseries 1) developed a profile of production, management, and profitability; 2) compared their performance to relevant U.S. benchmarks; and 3) identified trends and potential areas of improvement in the management of Australian nursery enterprises. The study confirmed that Australian nurseries incur high labor costs (38.8% of sales) comparable to United States nurseries, while costs of materials and supplies were lower than in the United States. Australian managers were concerned with marketing and recruiting and keeping labor rather than increasing capital investment to enhance production efficiency. Capital expenditures were funded from internal cash flow rather than external financing. Many of the nursery managers used relatively simple performance indicators, and most business objectives were stated in general terms. Concerns about the viability of the industry included oversupply, the growth in chain stores' business, factors eroding the demand for nursery products, and greater regulation.
Two sweetpotato [Ipomoea batatas (L.) Lam] genotypes (`Georgia Jet' and the breeding clone TI-155) were grown at 12-, 15-, 18-, and 21-h light/12-, 9-, 6-, 3-h dark cycles, respectively, to evaluate their growth and elemental concentration responses to duration and amount of daily lighting. Vine cuttings (15 cm long) of both genotypes were grown in rectangular nutrient film technique channels for 120 days. Conditions were as follows: photosynthetic photon flux (PPF) mean 427 μmol·m–2·s–1, 28C day/22C night air cycle, and 70% ± 5% relative humidity. The nutrient solution used was a modified half-strength Hoagland's solution. Storage root count per plant and per unit area, yield (in grams per square meters per day), and harvest index increased, while production efficiency (in grams per mole) decreased with increased daily PPF. Stomatal conductance for both genotypes declined with increased daily PPF. Leaves were smallest for both genotypes at the 21-h light period, while storage root yield declined as leaf area index increased. Except for a linear decrease in leaf N and K with increased light period, elemental concentration was not significantly influenced.