Yield, pest density, and tomato flavor effects of companion planting in garden-scale studies incorporating tomato, basil, and Brussels sprout

Companion planting is a small-scale intercropping practice often associated with organic or biodynamic gardening. Two garden-scale studies tested popular companion planting claims by comparing garden beds devoted entirely to one of three or more test crops (monocultures) to all possible two-crop mixtures (dicultures) of the same species. A third study evaluated effects of planting density and crop ratio in three dicultures using a novel experimental design to create gradients in both factors. All studies incorporated basil (Ocimum basilicum L.), Brussels sprout (Brassica oleracea L.), and tomato (Lycopersicum esculentum Mill.). A preliminary study also included snap bean (Phaseolus vulgaris L.), radish (Raphanus sativus L.) before Brussels sprout, and dicultures of tomato and Brussels sprout with a white clover (Trifolium repens L.) living mulch. Double blind taste tests over three years showed no consistent preference for tomatoes grown with companions over those grown in monoculture. An apparent inhibitory effect of companion planting on some pests of Brussels sprout (e.g. imported cabbageworm, Pieris rapae L.; striped flea beetle, Phylollotreta striolata Fab.) in the first study was reversed in the second study when earlier planting of Brussels sprout allowed it to compete more effectively with its companions. Relative yield indices calculated for a range of densities (1.1 - 47.2 plants/square meter) and crop ratios indicated advantages (mean = 20%) to planting either tomato or Brussels sprout with basil companions, but no advantage to planting tomato and Brussels sprout together. The highest yields in tomato, basil, and Brussels sprout monocultures occurred at inter-plant spacings of 25, 25 and 40 cm respectively, suggesting advantages to high-density planting. Yield advantages to diculture were most pronounced at the highest densities tested, and in dicultures incorporating the highest proportions of basil. Canopy light absorption and soil moisture content were inversely correlated, and the use of light and water resources was correlated with plant density and biomass production. I conclude that garden-scale intercropping can offer advantages over monoculture, but these are not achieved simply by combining certain compatible companion species. Crop densty, ratio, and relative planting times all affect the way that companion species interact with one another and their environment

Root Weevil (Coleoptera: Curculionidae) and Ground Beetle (Coleoptera: Carabidae) Immigration into Strawberry Plots Protected by Fence or Portable Trench Barriers

Physical exclusion shows some potential as a novel root weevil control strategy, but barriers to root weevil immigration may also exclude beneficial insects, such as ground beetles. A field study was undertaken in 1997 to assess the impact of two physical barriers—portable plastic trenches and aluminum fences with Teflon tape—on root weevil and ground beetle immigration into plots of strawberry, Fragaria x ananassa (Duchesne). Barypeithes pellucidus (Boheman) and Nemocestes incomptus (Horn), each comprised 43% of the root weevils caught at the site. Most (86%) of the ground beetles caught in control plots were longer than 1 cm, the width of the gap in the portable trench top. Trenches excluded 75 and 63% of B. pellucidus and N. incomptus, respectively, without significantly reducing immigration of large (<1 cm) ground beetles. Fences excluded 65, 84, and 99% of B. pellucidus, N. incomptus, and large ground beetles, respectively. Adding diatomaceous earth to trenches did not increase their efficacy, and fences without Teflon tape excluded ground beetles but not root weevils. The reduction in the population of root weevils and other strawberry pests caused by the use of barriers reduced damage to strawberry plant leaves and increased strawberry plant survival relative to unprotected control plots. Advantages and disadvantages of these physical control tools are discussed with a view to creating superior tools for root weevil exclusion, compatible with an integrated pest management approach. Portable trenches may offer a means of selectively excluding root weevils but not ground beetles

Can Sweet Sorghum and Sweetpotato Ethanol Contribute to Self-Sufficiency of Small Farms?

Sweet potato (Ipomoea batatas L.) and sweet sorghum (Sorghum bicolor L.) are promising crops for advanced biofuel production because they are better suited than corn (Zea mays L.) to low input production on small farms in the south. They can be considered advanced feedstocks only if lifecycle greenhouse gas emissions are less than 50% of basoline baseline emissions. Both sweet potato and sweet sorghum are multifunctional crops, with potential to simultaneously produce human food, animal feed, and biofuel feedstock. Kentucky State University is exploring the potential for organic production techniques and decentralized processing systems to reduce lifecycle greenhouse gas emissions of energy produced from these crops at a range of small farm scales. In 2009 biointensive production - a garden-scale strategy relying entirely on human labor - gave the greatest return to energy investment among the farm scales tested. Tractor-based small farm systems gave an inferior energy return in 2009, but a superior return to human labor in 2008 and 2009. A farmer’s decision to dedicate a portion of small-scale organic crop yield to on-farm ethanol production might be justified as a means of promoting self-sufficiency, resource cycling, or use of waste products, but ethanol feedstock production would be a poor economic choice as a principal means of income for the small organic farmer

Moisture tempers impairment of adult Otiorhynchus sulcatus (Coleoptera: Curculionidae) climbing ability by fluoropolymer, talc dust, and lithium grease

As part of a project to develop tools for the physical exclusion of flightless root weevils, adult black vine weevils (BVW), Otiorhynchus sulcatus (F.), were placed in open enclosures with smooth walls of glass, plastic or aluminum to test their ability to escape by climbing. Enclosure walls were left untreated or were treated with substances known to reduce insect climbing ability: fluoropolymer, powdered talc and lithium grease. No BVW escapes were observed under dry conditions, but all treatments allowed some escapes under wet conditions, suggesting that moisture helps BVW adults scale treated surfaces. The results help explain the ability of root weevils to overcome physical barriers under field conditions

Importance of Collection Overhangs on the Efficacy of Exclusion Fences for Managing Cabbage Flies (Diptera: Anthomyiidae)

Fine nylon mesh fences (135 cm high) with varying lengths of downward-sloping collection overhangs were evaluated for efficacy in excluding the female cabbage flies Delia radicum (L.) from plots of radish, Raphanus sativus (L.). During three trials conducted in 1994 and 1995, fences without overhangs, fences with 12.5-cm overhangs, or fences with 50-cm overhangs were tested against fences with standard 25-cm overhangs and unfenced control plots. In fenced plots with standard 25-cm overhangs, the mean number of D. radicum females caught on yellow sticky traps placed within plots was 85% less than those caught in corresponding control plots. The mean numbers of D. radicum females caught in fenced enclosures with no overhangs, 12.5-cm overhangs, or 50-cm overhangs, were 61, 67, and 94% less than those caught in corresponding control plots, respectively. The mean proportion of radishes damaged by D. radicum larvae inside enclosures with 25-cm overhangs was 62% less than in corresponding control plots. The mean proportions of radishes damaged inside fences with no overhangs, 12.5-cm overhangs, or 50-cm overhangs were 33, 59, and 81% less than those caught in corresponding control plots, respectively. Results are discussed in terms of defining an appropriate fence design for commercial use

Active specific immunotherapy of mouse methylcholanthrene induced tumours with Corynebacterium parvum and irradiated tumour cells.

The relative efficiency of active nonspecific or specific immunotherapy of developing methylcholanthrene induced fibrosarcomata with C. parvum was compared. For nonspecific immunotherapy, mice were challenged with tumour cells s.c. or i.v., and 2 days later injected i.v. with dilutions of C. parvum. The only significant effect was a retardation of s.c. tumour growth by the highest concentration of C. parvum (350 mug). However, active specific immunotherapy, using mixtures of C. parvum and irradiated or living tumour cells in the footpads, suppressed tumour growth when given at 2 or 6, but not 10, days after tumour challenge. Successful therapy required: sufficient tumour cells (greater than or equal to 5 X 10(4)); an optimal dose of C. parvum (5-120 mug, increasing with the number of tumour cells); an intact T cell system; the same tumour cells for challenge and treatment. The specificity was confirmed in a protection system in which treatment was given 7 days before tumour challenge. No protective immunity could be achieved with mixtures of C. parvum and foetal cells. Thus in this system C. parvum potentiates protective immunity only to the tumour unique TSTA

Mechanism of the anti-tumour effect of glucans and fructosans: a comparison with C. parvum.

The anti-tumour activity induced by glucans (lentinan, yeast cell walls, pseudonigeran, dextran, DEAE-dextran and dextran sulphate) and fructosans (levan and carboxymethyl-levan) was compared with the activity of C. parvum. The following effects on tumour systems in CBA mice were assayed: (a) adjuvant activity on the immune response against tumour-specific transplantation antigens (TSTA) with a methylcholanthrene-induced fibrosarcoma; (b) cytostatic activity of peritoneal macrophages against radiation-induced leukaemia cells; and (c) inhibition of tumour nodule formation in the lungs following i.v. injection of fibrosarcoma cells. All the polysaccharides induced cytostatic macrophages, but the dextrans and levans did so only after i.p. and not i.v. injection. Only lentinan, yeast cell walls and pseudonigeran were active in the lung-nodule inhibition test; and only lentinan and dextran sulphate showed slight adjuvant activity for TSTA. It is concluded that the anti-tumour activity induced by these polysaccharides is predominantly non-specific macrophage-mediated and much weaker than that found with C. parvum

Potential Use of Contraception for Managing Wildlife Pests in Australia

There is an increasing level of interest in contraception to manage wildlife pests in Australia, due mainly to concerns over high recurrent costs, animal welfare, and the failure of current control techniques to prevent damage in some instances. We have developed criteria that need to be met for contraception to be successful for pest control: • Technology exists to reduce fertility • An effective delivery mechanism to treat wild animals exists. • The end result of reduced animal damage is achieved. • Effects are humane and nontoxic. • Product is target specific, cost effective, and environmentally acceptable

Potential Use of Contraception for Managing Wildlife Pests in Australia

There is an increasing level of interest in contraception to manage wildlife pests in Australia, due mainly to concerns over high recurrent costs, animal welfare, and the failure of current control techniques to prevent damage in some instances. We have developed criteria that need to be met for contraception to be successful for pest control: • Technology exists to reduce fertility • An effective delivery mechanism to treat wild animals exists. • The end result of reduced animal damage is achieved. • Effects are humane and nontoxic. • Product is target specific, cost effective, and environmentally acceptable