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TemPeraTe Tree fruiT ProduCTioN sysTems

In document Agroecology - Gliessman (Page 112-117)

Carol Miles, David Granatstein, David Huggins, Steve Jones, and James Myers

5.3 TemPeraTe Tree fruiT ProduCTioN sysTems

Washington State has long been known for its large, red apples. Tree fruit production is the largest agricultural crop in the state, yielding over $1 billion in sales of packed fruit from some 200,000 acres of orchard land (WASS, 2002). Apple is the largest tree fruit crop, followed by pear and then cherry, with other tree fruits produced in relatively small amounts. Tree fruit production is concentrated in central Washington, just east of the Cascade Mountains, largely due to the favorable semiarid climate with a xeric (winter) rainfall pattern and dry, sunny summers. Irrigation is necessary to grow crops, but this means that moisture can be controlled and many diseases of tree fruits can be avoided. In addition, the insect pest complex is relatively modest

compared to other tree fruit production areas. During the winter season, snow is stored in the mountains and provides adequate summer runoff in most years to sup-ply high-quality surface water for the region’s irrigation needs.

5.3.1 primary FaCtors limiting sustainability

The three most significant limits to sustainability of fruit production are lack of profitability, shortages of labor, and limited water for irrigation. Tree fruit produc-tion has endured several cycles of prosperity and decline over the past century. The recent globalization of the fruit industry is perhaps the greatest challenge orchardists face in the near-term (O’Rourke, 2002). With labor generally accounting for about 40% of orchard production costs in Washington, and with Washington having the highest minimum wage law in the country (indexed annually to the rate of inflation), both cost of labor and its availability pose a threat to sustainability. Fruit producers in some countries have access to much cheaper labor and are developing the skilled workforce and infrastructure needed to deliver high-quality fruit to any market at a lower price than Washington can.

Aligning fruit production with consumer demand remains a challenge, as does returning profits to the grower. For example, Red Delicious had been the dominant apple variety for decades, accounting for some 70% of production. By the 1990s, how-ever, the variety was falling out of favor with consumers, and prices began to erode.

At the same time, new, more flavorful varieties appeared on the market. As a result, Red Delicious acreage has dropped substantially, while varieties unheard of 20 years ago, such as Fuji and Gala, are now major players. Growers now find themselves in a guessing game as to which new variety will catch on and prove profitable. This decision must be made each time an orchard is replanted at a cost of over $10,000 per acre. Whereas a planting might have lasted 20 to 50 years previously, growers now have no more than a 15-year period in which to recoup their investment.

Since rainfall is inadequate, reliable water supplies are needed for a perennial crop such as tree fruit. Certain irrigation districts have less reliable water supplies, particularly those that rely on runoff from mountain rivers with no reservoir storage.

Farms watered from the Columbia River generally do not have problems, but increas-ing competition for water in the Columbia River and regulations regardincreas-ing endan-gered salmon may lead to restrictions in the future. Global warming is expected to negatively impact the timing of water supply in the region, and this could impact fruit production. Also, due in part to new orchard systems that have reduced tree canopy density to allow more light penetration for fruit quality, water is now being used for evaporative cooling of orchards on extremely hot days to avoid sunburn damage. Climate change may also be exacerbating the sunburn problem. There is ample land with water rights on which to expand tree fruit production in the region if market demand increases.

Insect pests, particularly the codling moth (Cydia pomonella), have historically provided the greatest production challenge to apple growers (Beers et al., 1993).

Codling moth is a pest in apple production in most regions of the world. Being an introduced pest, there are no effective natural enemies for its control in cen-tral Washington and continual pesticide intervention has been used for more than a

century to prevent crop losses that can approach 100%. A succession of pesticides have been used, with many succumbing to insect resistance over time. These include lead arsenate, DDT, parathion, and azinphos-methyl. Newer pesticides that are more narrowly targeted and have lower human health concerns (e.g., insect growth regula-tors) are now available; however, insect resistance remains a challenge. The advent of pheromone mating disruption in the mid-1990s provided the first major nonpes-ticide control tool for codling moth, especially when adopted on an areawide basis over hundreds of contiguous acres (Calkins, 1998). Mating disruption seldom pro-vides stand-alone control, but when augmented with other strategies such as codling moth granulosis virus, spinosad, and horticultural oil, it provides the basis for a highly effective and affordable control program that also meets the National Organic Standards. Mating disruption has been adopted as a pest management strategy on more than 60% of the apple acres in Washington (Brunner et al. 2001), and under areawide management, codling moth damage dropped to near zero while pesticide use declined.

5.3.2 Conversion experienCes

Orchards have undergone some dramatic design changes during the past 20 to 30 years, with several sustainability implications. A shift from furrow irrigation to impact sprinklers to microsprinklers today (Williams and Ley, 1994) has led to sig-nificant water conservation and improved soil quality. The filtration required for microsprinklers also prevents weed seed incursion in the water. Traditional orchards had tall trees grafted onto seedling rootstocks, which formed a dense canopy. This canopy reduced light penetration and thus fruit coloring, and also made complete spray coverage for pest control difficult. In addition, workers had to use tall ladders to pick the crop, and injuries were common and costs were high. Trees also took five to eight years to come into full production, with the commensurate loss of income during that time.

During the 1980s, extensive research was conducted on high-density orchard plantings using dwarfing rootstocks (Barritt, 1992). This type of system originated during the 1950s in Europe in response to economic pressures and later a move toward integrated fruit production (El Titi et al., 1993). The dwarfing rootstock con-trols tree size to create more of a pedestrian orchard, where much of the work can be done from the ground or low ladders, saving labor time and reducing accidents.

The trees generally need support in the form of trellises or posts, and branches are trained to form a variety of canopy configurations that improve spray coverage, light penetration, and renewal wood. These systems will bear a commercial crop by the third year, with full production a year or two later, and a much higher-quality fruit is produced overall compared to the old system.

While the economic and social aspects of sustainability are addressed by this shift in orchard design, environmental gains are not a given. With more light reaching the ground, and with the reduced tolerance of the trees for competition with weeds, more weed control inputs are generally needed. Weed control is usually obtained through the use of herbicides or tillage. However, recent research on mulching sys-tems (Nielsen et al., 2003) has shown that this weed control strategy can reduce

water use and increase tree growth and yield up to 50% over the bare ground control.

Although pesticide options evolved independently of changes in orchard design, the low, open canopy did prove particularly well suited to the use of mating disruption dispensers when that technology appeared.

Sustainability in apple orchards has been impacted by changes in pesticide choices and strategies. The widespread adoption of synthetic insecticides after World War II led to outbreaks of pests that had not occurred before, especially mites such as McDaniel spider mite (Tetranychus mcdanieli) and European red mite (Panonychus ulmi) (Beers et al., 1993). An integrated mite management program for apples was initiated in Washington during the late 1960s to deal with the situation (Hoyt, 1969).

It focused on careful pesticide choice and timing, exploiting the fact that a key pred-atory mite (Typhlodromus occidentalis) had become resistant to organophosphate insecticides and thus was able to exert acceptable biological control if specific pesti-cides were used. This practice reduced pesticide costs from $85 per acre to $25 per acre and was widely adopted (Brunner, 1994). Subsequent research has developed insect phenology models that drive sampling and control decisions (Beers et al., 1993), track potential new biocontrol agents and enhance their habitat (Unruh and Brunner, 2005), and ultimately result in the implementation of “soft” pesticide pro-grams (Dunley and Madsen, 2005).

More recently, production of organic tree fruit in Washington has grown dra-matically. Organic apple acreage grew fourfold from 1989 to 1990 due to the Alar incident, but dropped off rapidly when growers were not able to adequately control codling moth (Granatstein, 2000) and prices plummeted due to a supply spike that the market could not absorb. As mating disruption provided control for codling moth, organic apple production grew from 1,300 acres in 1995 to 7,049 acres in 2004 (Granatstein et al., 2005). The semiarid climate makes the region particu-larly well suited for production of organic apples, pears, cherries, and other stone fruits. In a multiyear systems study comparing conventional, organic, and inte-grated apple production in the Yakima Valley of Washington State, Reganold et al. (2001) found that fruit yields were similar across all systems, with the organic and integrated systems exhibiting higher soil quality and less negative environ-mental impact based on a pesticide impact rating system. The organic system also produced improvements in fruit quality, higher profitability (with price premiums), and greater energy efficiency.

5.3.3 lessons learned

Dramatic changes in orchard sustainability have occurred since the 1950s due to the development and adoption of integrated pest management, the change in plant-ing design to high-density dwarf orchards, the adoption of newer, more desirable varieties, and more recently, the expansion of organic fruit production. Orchardists have proven their willingness to change and innovate, primarily for economic rea-sons, but with increasing appreciation for the environmental and social benefits that can accrue. While many orchardists have adopted organic production for eco-nomic reasons, they often experience other benefits from the sustainability of the organic system that they then extend to their conventional production acres. As

conventional production evolves, in part due to societal pressures for sustainability, the distinction among systems is beginning to blur as growers mix and match the best practices to fit their situation. Overall, this is leading to reduced use of the most disruptive and toxic pesticides, better water and nutrient management, improved conditions for workers, and higher-quality fruit. However, consistent profitability remains elusive, impacted more by retail consolidation and global market forces than by choices a grower may make.

5.3.4 indiCatorsoF sustainability

Among several key indicators of sustainability in tree fruit production, there are both positive and negative signals:

Pest control—

• Positive progress is being made in reducing pesticide use, but documented success in using beneficial insects within orchard systems to exert biocontrol of pests has proven more elusive.

Sources of nitrogen—

• Growers still rely on external sources of nitrogen, be they synthetic or organic. Although it is biologically feasible to grow the crop requirement of N in the orchard with legume cover crops, the chal-lenge is to integrate these cover crops into the orchard system without caus-ing other problems, such as excess N durcaus-ing fruit maturation and outbreaks of potentially damaging rodents and insect pests.

Energy use—

• All orchards rely on fossil fuels to run tractors, wind machines, and trucks, and the need to transport the fruit to distant markets leaves the tree fruit sector vulnerable to petroleum supply and cost impacts in the future.

Economic viability—

• The current push to mechanize more orchard operations aims to reduce production costs and boost competitiveness, but will have community impacts such as reducing certain types of jobs permanently.

Social factors—

• Workforce training programs such as the Latino Agricultural Education Program at Wenatchee Valley College represent an important investment in social sustainability. A key sustainability indicator is the number of remaining orchardists, and this number has steadily fallen, with both age and lack of profitability driving this decline.

5.3.5 ConClusions

Sustainability is being more widely discussed in the tree fruit sector, with integrated pest management, profitability, mechanization, and water use its more obvious mani-festations. Growers will continue to make positive stewardship changes to the degree that economics will allow them. New products (varieties), new strategies (“club”

varieties with restricted production), new health linkages (antioxidant content), and new ways for growers to participate in the value chain are all essential ingredients for economic sustainability. Simply cutting costs is unlikely to prove viable in the long run. Climate impacts on water supply and affordable energy may end up being the key determinants for the future of tree fruit production in the Northwest.

5.4 WheaT-Based ProduCTioN sysTems

In document Agroecology - Gliessman (Page 112-117)