Concern continues to rise over the adverse effects of the excessive use of chemically based agricultural pesticides, including herbicides, insecticides, nematicides, and fungicides. Important members of the U.S. agricultural scientific, producer, and policy communities have added their voices to those in the environmental, consumer, and public health arenas in pointing to the need for more benign and cost effective methods and systems of pest management and control. Indeed, the urgent need to further enhance the efficacy and use of such varied, yet interrelated, approaches to pest control as pathogens, predators, and parasites (traditional biological control), and such biologically based techniques as host plant resistance, natural plant products, semiochemicals, and autocidal methods, is now widely recognized in most agricultural circles.

Traditional agricultural systems are increasingly being recognized as important examples of ecologically sustainable production methods and as such deserve agroecological attention. In a study of terrace agriculture in Tlaxcala, Mexico, the authors identify several management features which have been used for as long as three thousand years. The theoretical approach employs the notion of open versus closed agroecosystems for examining soil and water management, species diversity, and nutrient cycling. In the traditional system, conservation of existing resources is the distinctive feature whereas, with modern techniques, the emphasis is on replacement. The most distinctive feature of the Tlaxcalan agroecosystem is the terrace/cajete complex which serves to contain heavy downpours and trap eroded soil, ensures diversity of plant species, and traps and concentrates nutrients. The functioning of this traditional system is endangered by new management strategies that have responded to external political, economic and social pressures for change. This article discusses the ecological repercussions of these new practices and suggests ways that appropriate elements may be integrated to promote the sustainability of food production.

This paper summarizes data from previous and current studies on two adjacent farms, one organically managed and the other conventionally managed, in the Palouse region of eastern Washington. The 320-hectare organic farm has been managed without the use of commercial fertilizers and only limited use of pesticides since the farm was first plowed in 1909. The 525-hectare conventional farm, first cultivated in 1908, began receiving recommended rates of commercial fertilizers and pesticides in 1948 and the early 1950's, respectively. The organically-farmed Naff silt loam soil had significantly higher organic matter, cation exchange capacity, total nitrogen, extractable potassium, water content, pH, polysaccharide content, enzyme levels, and microbial biomass than did the conventionally-farmed Naff soil. Also, the organically-farmed soil had significantly lower modulus of rupture, more granular structure, less hard and more friable consistence, and 16 centimeters more topsoil. This topsail difference between farms was attributed to significantly greater erosion on the conventionally-farmed soil between 1948 and 1985. The difference in erosion rates between farms was most probably due to their different crop rotation systems; Le., only the organic farm included a green manure crop in its rotation, and it had different tillage practices. These studies indicate that, in the long-term, the organic farming system was more effective than the conventional farming system in maintaining the tilth and productivity of the Naff soil and in reducing its loss to erosion.

Biological control is defined broadly as the “use of natural or modified organisms, genes, or gene products” to reduce the effects of pests and diseases. Physical control is the use of tillage, open-field burning, heat-treatment (pasteurization), and other physical methods, usually to eliminate pests or separate them from the crop. Chemical control is the use of synthetic chemical pesticides to eliminate pests or reduce their effects. The many approaches to biological control can be categorized conceptionally into 1) regulation of the pest population (the classical approach), 2) exclusionary systems of protection (a living barrier of microorganisms on the plant or animal that deters infection or pest attack), and 3) systems of self-defense (resistance and immunization). The agents of biological control include the pest- or disease-agent itself (sterile males or avirulent strains of pathogens), antagonists or natural enemies, or the plant or animal managed or manipulated (immunized) to defend itself. The methods range from 1) conserving and making maximum use of indigenous (resident) biological control through cultural practices, 2) making one-time or occasional introductions of genes or natural enemies that are more or less self-sustaining and 3) making repeated introductions of a biocontrol agent (e.g. a microbial pesticide). Biological, physical, and chemical treatments and pest controls can be integrated into holistic plant-health care also known as integrated crop and pest management. Eight principles of plant health care are offered: 1) know the production limits of the agroecosystem; 2) rotate the crops; 3) maintain soil organic matter; 4) use clean planting material; 5) plant well-adapted, pest-resistant cultivars; 6) minimize environmental and nutritional stresses; 7) maximize the effects of beneficial organisms; and 8) protect with pesticides as necessary.

Crops grown on sand and gravel spoil areas are subject to temperature, moisture, and nutrient stresses due to the infertile, acidic, and coarse-textured properties of the spoil material. Additions of organic materials such as feedlot manure and sewage sludge compost applied at rates of 40, 80, and 160 Mg/ha were found to improve these spoil areas by providing (1) a more favorable pH for seedling germination and root development, (2) essential crop nutrients, and (3) a greatly increased water content of the spoils in the treated plots compared to fertilized controls. The manure-treated spoil plots had a higher water content than either the compost-treated spoils or the limed and fertilized control plots. In a drought year when the wastes were reapplied, both grain and stalk yields of sweet corn were highest for the manure-treated plots. The low heavy metal content makes these organic materials safe for use as soil conditioners. In addition, uptake and accumulation of toxic metals by sweet corn is generally less than other crops. The interaction between the kind and rate of organic amendment applied, the amount of rainfall in any given growing period, and the water content of the treated spoils determined the final nutrient composition of the stalks, leaves, and grain, as well as the grain and stalk yield.

Biological control of arthropod pests has a long history of useful practical application. Parasites, predators, and pathogens have been employed in many cases to control pest arthropods in an efficient, cost-effective, and permanent manner. The traditional tactics used in biological control (classical, augmentation, and conservation) remain vital and valuable tools in the biological control of pests for agricultural crops, range lands, forests, and glasshouses. New technologies offer promise. One emerging technique involves the genetic improvement of natural enemies of arthropods through selection, hybridization, or recombinant DNA technology.

One of the major gaps in the empirical literature comparing conventional and organic farmers is the degree to which conventional farmers would prefer or can be motivated to use reduced-input practices comparable to those of alternative agriculturalists. This paper presents the results of a 1987 survey of a random sample of New York farm operators and a two-thirds sample of the membership list of the New York State chapter of the Natural Organic Farmers Association (NOFA-NY). The results show that while conventional farmers tend to have a lower preference for reduced-input practices than do alternative agriculturalists (NOFA-NY members), conventional farmers tend to prefer pest- and disease-resistant crop varieties, nonpurchased, on-farmproduced sources of fertility, and nonchemical means of disease control over high-input, chemically-based production practices. The largest differences between conventional and alternative agriculturalists are with respect to preferences for weed control practices. For six of the eight practices assessed, operators of small farms (annual gross sales less than $40,000) were intermediate in their preferences between commercial-scale farmers (gross sales $40,000 or more) and alternative agriculturalists. There was, however, virtually no difference between conventional and organic farmers in their tillage practice preferences; similar percentages of the NOFA members and commercial-scale farmers preferred minimum tillage practices, while the percentage of small farmers preferring to use as few tillage operations as possible was lower than that of both commercialscale and organic farmers. Differences between conventional and organic farmers in their production practice preferences are far smaller than differences in their environmental orientations.

Moderate to large scale California growers (as well as small scale ones) manipulate cropping patterns in a number of ways to reduce pest problems. Crop rotation, which can be defined as diversifying crops over time, is used to manage selected pests, primarily weeds, pathogens, and nematodes. As a substitute for pesticides, crop rotation has been most rewarding in the control of nematodes; sugarbeet cyst and root knot nematode examples are detailed. Some pests that invade fields from nearby areas can be managed by modifying adjacent cropping patterns or practices; Pierce's disease of grapes, sugarbeet yellows and border harvesting of alfalfa are given as examples. Finally, multiple crops can be grown within a single field or orchard. Although this approach is not widely practiced by many California growers, two examples of systems where intercropping has been shown to limit pest numbers without the use of pesticides are described: intercropping of cotton with alfalfa and companion planting oats when seeding alfalfa. These examples show that using crop diversification to manage pests is feasible, but growers must be strongly motivated to make the necessary changes in cropping patterns. Most of the systems that have been widely adopted are those for which few other economically feasible methods were available.

A shortage of effective, non-chemical pest control measures is a major constraint to more widespread adoption of sustainable agricultural practices. Overcoming this constraint with biological pest control tactics appears to be an attainable goal but will require substantial public sector support. Biological agents that are self-perpetuating do not offer profit incentive to private industry. On the other hand, microbial pesticides, which do require annual application, often are so highly specific for particular pests that the private sector is unable to risk venture capital for their development. Collaboration between public- and private-sector scientists is essential for biological pesticide development. In the U.S., a model working relationship for technology transfer between the private and public sector has been achieved with two commercial mycoherbicides, Collego™ and DeVine™. The model illustrates the strengths of the public sector for creating and storing fundamental knowledge of biological interactions at the organismal and ecosystem levels, also the capability of the private sector for large-scale production of fungi, for drying labile, living products, for effective patent protection, for satisfying EPA registration requirements, and for the commercial distribution, marketing and servicing of agricultural products. From three perspectives-biological, technical, and commercial—the success of Collego™ and DeVine™ has provided a definite step in the quest for low-cost weed control methods that are not hazardous to the environment nor in ground water. These successes also provide a model for an approach to reducing the dependence of agriculture upon chemical herbicides, the most extensively used chemical pesticides in agricultural production, likewise a useful insight toward technology that can lead to more widespread adoption of low-input, environmentally compatible and sustainable agricultural production.

Research plots that are large enough to accommodate regular farm machinery are thought to contain too much field variation to allow reliable interpretation of experimental results. This study was conducted to determine whether experimental error was controlled on a wide variety of agricultural field trials that used plots larger than normally used by researchers. The investigation included trials conducted on an experiment station and trials conducted on actual commercial farms. The planning and management of the experiments ranged from those completely conducted by university researchers to those completely done by farmers.

The level of experimental error in all the trials was well within the limits normally accepted by researchers in agronomy. Plots ranging in length from 125 to 1200 feet and as wide as one or two passes of standard farm machinery gave experimental results that were statistically sound. Statistical requirements for randomization and replication were all met.

The ability to use large plots and farmer participation enhances the testing of new technology on farms. This leads to new opportunities to test crop production factors in a systems setting under actual farm conditions. The statistical reliability of the on-farm designs analyzed in this study should increase cooperation among researchers, extension workers, and farmers in research activities.

Weed seed consumption experiments involving comparison of rates of seed loss by seed feeders were conducted over a five-week period in low-input (no insecticide, low herbicide usage) conventional- and no-tillage soybean agroecosystems. Seeds of four broadleaf weed species (ragweed [Ambrosia artemisiifolia L.], pigweed [Amaranthus retroflexus L.], sicklepod [Cassia obtusifolia L.], and jimsonweed [Datura stramonium L.]) and one grain crop species (wheat [Triticum aestivum L.]) were provided in a free choice design at densities of 10, 25, and 50 seeds/24 cm3. Approximately 2.3 times more seeds overall, and 1.4 times more large seeds as a group were consumed in notillage systems than in conventional-tillage systems. In our experimental low-input, notillage treatments, large ground beetles (Carabidae: Coleoptera) (15–25 mm) and mice preferentially fed on the larger seed species, while small carabids (< 15 mm), ants and crickets, fed almost exclusively on the smaller seed species. Carabid beetles were responsible for more than half of all seeds consumed. Laboratory and field studies indicated that ground beetles selectively consumed specific seed species. In conventional-tillage, ants were one of the dominant consumers of seeds, suggesting different patterns of resource partitioning in each tillage system. We suggest that selective feeding by arthropod seed feeders, in combination with their high number, could affect the species composition and possibly the abundance of weeds in low-input, no-tillage agroecosystems.

CASST™ herbicide (Alternaria cassiae,) has been shown to be an effective biological control agent for sicklepod ("Cassia obtusifolia LJ, coffee senna ("Cassia occidentalis L.) and showy crotalaria ("Crotalaria spectabilis Roth). Current research has shown the potential of this mycoherbicide for use both alone and integrated with other herbicides as an effective commercial control measure for these troublesome weeds.

The U.S. public is expressing strong preference for the use of biological control methods in the management of U.S. agricultural, forest, and rangeland insect pests. This follows from a widespread understanding among citizens that synthetic insecticides have potentially harmful side effects on humans and that they are spreading increasingly as pollutants in the environment. Major recent increases in the number of pesticide-resistant insect species also put pressure on the agricultural community toward adoption of alternative non-agchemical plant and animal protection strategies. Movement in the direction of such alternatives has been facilitated by the fact that in the last two decades much progress has been made in Integrated Pest Management (IPM) through an improved understanding of the interactions of pests with their hosts. In that time period, many advances have been made in describing and predicting insect movement, seasonal cycles, and the effects of secondary plant compounds on insect reproduction. Simultaneously, much has been learned about the behavior, physiology, and population dynamics of insect parasitoids, i.e. parasites on insect pests. In the 1990's and subsequently, Biological Control Intensive Pest Management (BCIPM) will require continuing research to attain needed advancement in knowledge of growth and development of host plants, population dynamics of pests and parasitoids, and ecology of secondary pests that may interfere with implementation of BCIPM programs. Extension and research personnel will then be increasingly able to devise useful control methods for pests within selected cropping systems. We describe here examples to illustrate present and potential future use of BCIPM in different practical plant systems in New Jersey.