Chapter 2
Selecting a Winning Site and Crops to Match
The ideal orchard site is one where the climate, soils, irrigation, topography, and surrounding land uses are well suited to producing the crops and varieties that you want to grow. For commercial fruit growers, access to the site, support services, and legal restrictions are also important.
Many orchard problems come from growing crops and varieties in locations where they are poorly or marginally adapted. On a small scale, this is not usually a serious issue. Experimenting is part of the fun of a hobby orchard, and the worst that can happen is that you may have to replant a few trees. Even for the smallest orchard, however, growing crops and varieties that are healthy, productive, and relatively easy to produce is more fun than struggling for mediocre results.
The situation becomes more serious as orchard size and investment costs increase. Purchasing land and establishing a large orchard are long-term decisions that are difficult and expensive to change. Loss of trees and crops and the extra care required to produce varieties poorly matched to a site can make your enterprise unprofitable. Fruit growing should be fun and, for some, profitable. That starts by picking a winning site.
This chapter is designed to help you pick out a great orchard site and to match crops to your growing conditions. For those who already own their orchard sites and have trees planted, this chapter is still important because it will help you evaluate your site with the goal of improving it. At this time, you should also consider how you plan to market your crops because this will impact which crops you choose and how you set up your orchard. See chapter 14 for more information about marketing.
Climate
Climate sets the limits within which all other factors operate. Summer and winter temperatures, length of the growing season, the amount of heat available during the growing season, precipitation, humidity, and, depending on where you live, wind, all play key roles in growing fruit. The important thing to recognize is that “climate” is not the same as “weather.” Climate refers to temperature and precipitation patterns measured over decades. Weather, on the other hand, is what you see out the window at any given moment.
Fortunately, the information you need to evaluate your climate is available online for Canadian and U.S. locations. The National Oceanic and Atmosphere Administration (NOAA) Regional Climate Centers provide localized climate records for the entire United States (see Resources). The National Climate Data and Information Archive provides similar information for Canada (see Resources). Unfortunately, the Canadian database does not provide information on average frost dates, growing season lengths, and heat units. Some regional Environment Canada websites help fill in this information. Agricultural specialists at provincial Ministry of Agriculture offices can be good sources of information on climate as it relates to crop production in a given area. In the United States, state and county Cooperative Extension offices often have information on climate and fruit crop selection and production.
Think long-term in choosing a site and crops. Orchard crops are very long-lived. Depending on the crop, some trees and bushes can easily remain productive for 75 years or more. In a commercial orchard, 15 to 20 years is a good productive life expectancy, due more to shifting consumer preferences than the productivity of the trees.
Winter Temperatures
Winter temperatures are the first factors to evaluate. Northern growers need to consider the risk of freezing injury to tree trunks, branches, and buds from late fall through early spring. Southern growers are concerned with the accumulation of chilling units, which temperate zone fruit trees need to meet their dormancy requirements and develop new shoots, leaves, and fruit each spring.
Temperate zone plants require a dormant or rest period during the winter. Shorter days and cool night temperatures trigger the trees’ entry into dormancy. Physical and chemical changes take place in the buds, bark, and wood that allow them to survive winter temperatures.
Once trees are dormant, they must spend a certain amount of time at temperatures between about 32 and 55°F (0 and 13°C), during which time chilling units accumulate. Chilling units accumulate most rapidly near 45°F (8°C). Temperatures below 32°F (0°C) do not contribute to chilling, and temperatures of 70°F (21°C) or more for as little as 4 hours can actually reverse chilling that has already occurred. Without the necessary chilling, the trees will be unable to bloom, leaf out, or grow normally.
Different varieties, even within the same crop, can have very different chilling requirements. High-chilling apples, for example, require more than about 800 hours of chilling; medium-chilling apples need 400 to 800 hours; and low-chilling apples require 100 to 400 hours. Of good news to warm-climate growers, fruit breeders have made excellent progress in developing “low-chilling” varieties, extending the range for traditionally northern fruits further south. Be very careful to match your crops and varieties to your site. We’ll cover varieties in detail in chapters 5 and 6.
Several different models have been developed to calculate chilling units for a given location based on weather records. A discussion of those methods, however, goes far beyond what we can or need to do here. The U.S. Department of Agriculture (USDA) Plant Hardiness Zone Map (see box on page 21), combined with extreme minimum winter temperature data for your site and the recommended zones for different varieties, will give you a good start on selecting crops and varieties. Fruit growers, gardener groups, and Cooperative Extension educators and specialists can help you fine-tune your selections.
A good strategy is to select plants rated one or two zones hardier than your location. For example, Mansfield, Pennsylvania, is designated USDA Zone 5b, with average minimum temperatures between −10 and −15°F (−23 to −26°C). An orchardist in Mansfield might want to select varieties rated to Zone 4 (−20 to −30°F [−29 to −34°C]) to reduce the risk of freeze damage during an unusually severe winter. In the case of the Pennsylvania grower, ‘Honeycrisp’ apple (Zones 3 to 6) may prove more reliable in the long term than ‘Jonafree’ (Zones 5 to 8). (Note that while the map is broken down into two ranges per zone [5a, 5b, etc.], plants are typically rated to whole zones [4, 5, 6, etc.].)
A word of caution! I have found that growers typically overrate how warm their sites are and how cold-hardy their plants are. If you are conservative and objective in evaluating your site and selecting your crops, you will have a more successful and enjoyable time growing fruit.
Spring and Summer Temperatures
Spring temperatures are critically important to orchardists. Of primary concern are killing freezes prior to bloom and frosts during bloom. During deep dormancy, tree fruit buds can tolerate temperatures ranging from about −15°F to −40°F (−26 to −40°C). During spring, the plants quickly lose their cold hardiness and open blossoms are killed at about 28°F (−2°C).
Sites with warm springs but frequent frosts make tree fruit production difficult. This is especially true for stone fruits and Asian pears, which bloom earlier than European pears and apples. Trees located on north-facing slopes bloom later than those in sunnier locations — an advantage where spring frost damage is a problem. If your orchard is located on a frosty site, late-blooming varieties provide a distinct advantage. You may also need to provide frost protection during and shortly after bloom.
Locations near the ocean or along the eastern shores of large lakes are often excellent for orchards. The water acts as a thermal shock absorber, cooling the orchard and slowing bud development in the spring while reducing the risk of spring frost. Because weather typically moves from west to east in the Northern Hemisphere, western shores of lakes have less influence on orchard temperatures than eastern shores. In northwestern Montana, for example, sweet cherries are grown commercially in a narrow strip along the eastern shore of Flathead Lake. Just a few miles away, sweet cherry production becomes very difficult due to spring frosts. Likewise, the eastern shores of the Great Lakes host varied and abundant orchards, made possible by the moderating influence the water has on nearby temperatures. In general, the larger the body of water, the greater its influence on temperatures.
Summer temperatures are important factors for cool-climate orchardists in terms of the heat units available to produce and ripen fruit crops. While most stone fruit varieties ripen wherever they can be grown in North America, some pome fruit varieties require long, warm summers to mature. In short-season areas, early-maturing fruits are generally more reliable and productive.
USDA Plant Hardiness Zone Map
The map (see below and available online) divides the United States into 13 hardiness zones based on average minimum winter temperatures. While other hardiness zone systems have been published, the USDA map is the most comprehensive and universal for North America.
This updated map, released in January 2012, expands from 11 to 13 hardiness zones and updates the zones based on recent weather data. Unfortunately, the 2012 edition does not include Canada, as earlier versions of the map did. For Canadian growers, the 1990 version of the map is still available for downloading on the USDA site under the tab “Map and Data Downloads.” (see Resources). The zones may have shifted slightly but will still give you a starting point for selecting crops and varieties. In general, you may find that your location would now be rated about one-half zone warmer than previously.
The new map is based on 30 years of temperature data, rather than 13 years used for the original map. Also, it turns out that the original 13-year period was unusually cold. Hardiness zone classifications in the new map tend to be slightly warmer than under the original map for many locations.
Fruit trees are typically rated for a range of hardiness zones. ‘Harglow’ apricot, for example, is recommended for hardiness Zones 5 to 8 and is well suited for orchards from the mid-southern United States into Canada. At the other extreme, tropical and subtropical loquat trees are rated to Zones 8 to 12 and are grown commercially and in home orchards in the United States in the warmer parts of Florida, coastal Georgia, Hawaii, and southern California.
When using hardiness zones to select crops, remember that the system is based on average minimum temperatures. For a long-lived plant, such as an apple or cherry tree, the average temperature has little meaning. The real question is, what is the likelihood of a killing freeze during the expected life of your orchard? By using both the hardiness zone map and extreme minimum winter data available from the climate databases mentioned above, you can make an informed choice (see box on page 25).
Table 2.1
Plant Hardiness Zone Map Categories
Each numbered rating is based on the average minimum winter temperature experienced at a site. Ratings are further divided into smaller categories designated by the letters “a” and “b.”
Precipitation and Humidity
Arid locations with ample irrigation water are often ideal for orchards. The lack of rainfall during spring and summer greatly reduces apple scab, brown blight of stone fruits, fire blight, and other diseases compared to what you find in more humid areas. The higher precipitation levels and humidity east of the Rocky Mountains do not mean that you cannot grow orchard fruits organically, but it will be more challenging than for western growers. If you live in a rainy or otherwise humid climate, it is particularly important to select a site with excellent air drainage, improve the air movement on your site, and select disease-resistant crops and varieties. We’ll discuss some approaches to modifying your orchard environment in later chapters.
Late spring and early summer rains can cause serious problems for cherry growers. The fruits are susceptible to cracking when rains come just as the fruits are ripening and into the harvest season. Some varieties are less prone to cracking than others. For rainy areas, it is important to select cracking-resistant cherry varieties.
How to Select Crops That Are Hardy for Your Site
- 1. Identify your hardiness zone using the hardiness zone map or table 2.1 on page 21. For example, Sandpoint, Idaho, is rated as Zone 6a (−5 to −10°F; −21 to −23°C).
- 2. Look up the extreme minimum winter data for your area using the NOAA Regional Climate Center website if in the United States, or the website of the National Climate Data and Information Archive if in Canada (see Resources for both websites). For Sandpoint, temperatures of −20°F (−29°C) are common, and the recorded low is −36°F (−38°C).
- 3. Compare the two sets of data to select a crop that will be hardy enough to withstand the winter temperature extremes that may occur during the life of your orchard. For Sandpoint, you may want to select a variety rated to Zone 5a or even 4a.
Precipitation and humidity affect your irrigation practices. You want to provide enough water through precipitation and irrigation to meet the needs of the trees without forcing lush growth or encouraging root and collar rots. The rule is to keep the soil moist without waterlogging it.
The amount of precipitation your orchard receives will also have an impact on pests and diseases. If you grow tree fruits organically in a humid, high-rainfall area, be prepared to spend more for pest and disease management and have lower packouts of premium fruit than conventional growers in your area or organic growers in ideal climates. Before investing heavily in a commercial operation, be sure that your market will support the higher prices you will need to charge (called an organic premium) in order to earn a profit. Design your operation to market that portion of your crop that does not meet the high-quality standards for premium fresh markets; cider and processing are two options.
Important Temperatures
−15° to −40°F (−26 to −40°C): Depending on variety, tree fruit buds can tolerate some figure in this range during deep dormancy
28°F (−2°C): Blossoms are killed
32 to 55°F (0 to 13°C): Chilling units accumulate
45°F (7°C): Optimum temperature for chilling unit accumulation
Above 70°F (21°C): Chilling can be reversed if temperature maintained for 4 hours or more
Winds
Wind damage is not a serious problem in many fruit-growing areas of North America, but there are exceptions. Frequent and prolonged wind can tatter leaves, dry out soil, and desiccate trees, the last of which is particularly a problem during subfreezing temperatures in winter. Winds can rub the fruit against branches and other fruits, causing bruises and scarring. Wind can also cause trees to lean, and the trees may require trellising to stay upright and properly trained.
If you are in an area known for frequent winds, it is a good strategy to select an orchard site on a bench (a more-or-less level area on a slope above a valley floor) or gentle slope facing away from the prevailing winds. Another option is to plant a windbreak of taller trees around your fruit trees to protect them. Windbreaks are common, for example, around orchards along both sides of the Columbia River in Washington and Oregon. Windbreaks can also be useful in the High Plains, the Prairie Provinces, and parts of the Midwestern United States.
Soils
Soils are one of the most important considerations in selecting and managing an orchard site. They are, quite literally, the foundation for your orchard. One of the most important steps in selecting or managing an orchard site is to test the soil. Soil test kits are available from garden centers and horticultural suppliers, but many do not provide adequate or accurate data. It is best to have your soil samples analyzed by a commercial or university laboratory that is familiar with the soils in your area. Because soils differ as you move from one region to another, different tests and interpretations are used.
In general, you will want to have your soil tested for pH, organic matter, buffering capacity, cation exchange capacity (CEC), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), and boron (B). If you are in an arid location or are planting on land that has been fertilized or irrigated, include a salinity (electrical conductivity or EC) test. Laboratories have standard tests, such as an extended fertility test, that may include additional nutrients. If you do not know what type of soil you have, a particle size distribution (PSD) analysis will be important in helping you develop soil management practices. Figure 2.2 shows a sample soil analysis report.
While much is made of soil fertility in crop production, soil nutrients are relatively easy to adjust, particularly when establishing a new orchard or replanting. The purpose of a preplant soil test is to establish baselines that will help you choose what amendments, if any, to add and how much of each. Chapters 4 and 8 address soil nutrition and fertilization.
Soil Types and Drainage
Even before we begin looking at soil pH and organic matter, consider soil drainage. With few exceptions, tree fruits perform best on deep, well-drained soils, and many problems encountered by orchardists can be traced to inadequate soil drainage. Provided that irrigation water is available, trees survive and produce much better on an excessively well-drained site than one that is too wet. Root rot is an obvious problem with wet soils, but poor drainage impedes the movement of oxygen to the roots and the movement of carbon dioxide out of the soil, and it interferes with nutrient uptake. Wet soils also warm slowly in the spring, interfering with tree growth and adversely affecting soil micro- and macroorganisms.
Classifying types. The type of soil, referred to as soil texture, has much to do with water drainage. We classify soils by their relative percentages of sand, silt, and clay. Sand particles are the largest and do little more than provide water drainage, gas exchange for the roots, and anchorage for tree roots. Sand does not hold water or nutrients well. Silt particles are the next smallest and hold water and greatly help form soil aggregates. Clay particles are the smallest soil particles. They help with aggregate formation and hold water and nutrients.
An effective blend of the three types of soil particles provides good water- and nutrient-holding capacity, but also good water drainage, gas exchange, and root penetration. Soils that are too sandy are droughty and require much irrigation. Heavy clay soils drain poorly and encourage root disorders.
Figure 2.3 shows how soils are classified, based on their percentages of sand, silt, and clay. To use the triangle, locate the percentage of sand, silt, and clay in your sample. Starting at those points, draw lines parallel to the adjacent counterclockwise side. Guidelines are shown in the figure. The point where the lines intersect is your soil type or texture. Say, for example, your soil particle size distribution test showed sand = 45 percent, silt = 35 percent, and clay = 20 percent. The classification for this sample would be loam — an excellent choice for orchard soil, provided that it is deep enough and well drained.
Soil types and crops. Loam and sandy loam soils are excellent for tree fruits. Given ample irrigation water, even loamy sands support orchards. With proper steps to ensure water drainage, silt loam soils can be effective orchard sites. Heavier-textured soils make tree fruit culture difficult. You can modify soils by adding organic matter to improve water-holding capacity, soil tilth, nutrition, and biological activity. Be aware, however, that simply mixing large quantities of organic matter into heavy soils can make a bad situation even worse by increasing water-holding capacity. Adding sand to improve soil drainage is usually prohibitively expensive on all but the smallest sites.
Soil drainage requirements differ among pome and stone fruits. In general, European pears tolerate heavy soils better than do other common tree fruit crops, followed by apples. Some apple and pear rootstocks perform much better on poorly drained soils than others. For example, M26 apple rootstocks produce trees about 8 feet tall and are generally popular. M26 rootstocks, however, perform very poorly on heavy or otherwise poorly drained soils. In such cases, a grower might choose a Bud9 apple rootstock, which is more tolerant of heavy soils than M26. Stone fruits are less tolerant of heavy soils and poor drainage than apples and pears. Peaches, in particular, tend to grow and produce poorly when water drainage is inadequate.
I maintained a teaching orchard for 15 years, demonstrating different crops, varieties, rootstocks, and production practices. The orchard was located on a site with 8 to 12 inches of silt loam overlying 4 feet of fractured clay. Not an ideal site. European pears flourished. Apples on some rootstocks performed well, while other rootstock/variety combinations were severely stunted or died. Sweet cherry trees grew vigorously, while tart cherries suffered trunk splitting. The plum trees apparently grew well but had exceptionally poor anchorage. During a fruit growers’ tour one spring, we discovered that some of my 15-foot-tall plum trees had literally fallen down. For me, it was embarrassing. For a commercial orchardist, the situation would have been far worse. Poorly drained sites are poor choices for orchards. If you must grow your fruit trees on poorly drained soil, you will need to take extra steps to improve water drainage in the root zone.
Examining your soil. If you are considering a commercial orchard site, an excellent practice is to dig several trenches, each 6 to 10 feet deep, with a backhoe. Examine the soil profile for clay lenses, hardpans, and deep gravel or sand layers. Be especially alert for dark grayish-blue to greenish-black, sometimes foul-smelling, layers that indicate waterlogged soils. This type of discoloration is called gleying.
Hardpans and clay layers that are not too deep can sometimes be broken up with a chisel or rip plows. These implements may be mounted on a tractor or bulldozer and consist of long shanks (and sometimes feet or blades) that extend deep into the soil. For shallow ripping on light-textured soils, a medium-sized tractor might suffice. For deep ripping on heavy-textured soils, you will need a large tractor or bulldozer.
Sandy and gravelly soils can be suitable for an orchard if you have adequate irrigation water and access to ample supplies of organic materials suitable for amending soils. Be very wary of waterlogged soils, however. Determine why they are waterlogged, and be sure you can develop adequate drainage before attempting to plant fruit trees on them. We’ll cover specific ways to correct drainage problems in chapter 4.
By digging trenches, you can estimate rooting depth. Ideally, you should have 5 feet or more of rooting depth for fruit trees and a water table that remains at least 3 feet below the soil surface. You can certainly grow fruit trees on shallow soils, but doing so is more challenging than on deeper soils and may not be suitable for all fruit crops.
The types of vegetation growing on your orchard site will also give you information about your soil. Cattails, sedges, rushes, reeds, and certain grasses and other plants that are associated with wetlands or otherwise poorly drained soil are a giveaway that this location is not a good choice for an orchard.
Soil pH
Soil pH is usually manageable in most parts of the United States and Canada. The term pH refers to the soil’s acidity or alkalinity, which has a profound influence on the availability of soil nutrients to plants. Soils with pH values less than 7.0 are acidic, while pH values above 7.0 indicate alkaline soils. Although an optimum soil pH for fruit trees is between 6.5 and 7.0, pH values ranging from 5.5 to 7.5 seldom create serious problems for most fruit tree crops.
Soils that are too acidic are seldom a serious problem for fruit trees because raising the soil pH with limestone or dolomite is generally straightforward and relatively inexpensive. Orchard management practices can be devised to help maintain an elevated soil pH.
Excessively alkaline soils are more challenging. As soil pH rises much above 7.5, fruit trees begin showing symptoms of iron chlorosis and other nutrient disorders. Yellow to yellowish-white leaves with green veins are the classic symptoms of iron chlorosis, which also includes stunted growth, poor yields, and even tree death. While iron chlorosis can be caused by a lack of iron in the soil, which sometimes occurs on acidic, organic soils, by far the most common cause is high soil pH. In these cases, iron may be abundant in the soil but is in a chemical form that is unavailable to the trees. Excessive concentrations of some other nutrients, such as phosphorus, can interfere with the uptake and utilization of iron. Iron chlorosis is particularly common on wet, cold soils.
Orchard soils can be acidified and iron can be added to the trees in foliar sprays, but these practices increase the work and costs of the establishment and maintenance of the orchard. By far the best orchard sites have well-drained soils with pH values roughly between 5.5 and 7.5. We’ll discuss how to adjust soil pH in chapter 4. For now, be aware that growing fruit crops on soils with a pH above about 7.5 is more difficult than doing so on neutral or slightly acidic soils.
Soil Salinity
Salty (saline) soils can be a problem in some regions of North America, particularly on arid sites. Even in areas with relatively abundant precipitation, saline soils can develop due to excessive applications of fertilizers, including manures. Frequent, shallow irrigation dissolves salts and concentrates them near the soil surface as the water evaporates. Many horticultural crops are sensitive to high concentrations of salts and perform poorly on such soils.
Soil salinity is measured with electrical conductivity meters. Reporting units vary from one laboratory to another and include micromhos per centimeter (µmho/cm), millimhos per centimeter (mmho/cm), deciSiemens per meter (dS/m), and a few other units. Fortunately, it is easy to convert between units: 1000 µmho/cm = 1 mmho/cm = 1dS/m.
Soils with salinity levels of 0 to 2,000 µmho/cm (0–2 mmho/cm or 0–2 dS/m) are considered nonsaline and are suitable for all crops. Salinity levels between 2,000 and 4,000 µmho/cm (2–4 mmho/cm or 2–4 dS/m) indicate a very slightly saline soil and can create problems in sensitive plants, including blueberries, raspberries, and strawberries. Tree fruit crops tolerate very slightly saline soils better than their berry counterparts and can generally be grown on soils with salinity levels of 4,000 µmho/cm or less (4 mmho/cm or 4 dS/m), providing the soils are otherwise acceptable. For soils with salinity levels greater than 4,000 µmho/cm that cannot be reclaimed by leaching with large amounts of low-saline water, the production of horticulture crops is limited to a few vegetable crops, including beets, broccoli, squash, tomatoes, and asparagus.
Particularly troublesome are saline-sodic soils found in the American west. The abundant sodium and other ions in these soils interfere with the formation of soil aggregates that are necessary for water drainage. Such soils form slick, sometimes oil-colored, deposits that do not support plant life. Saline soils can be reclaimed, in some cases, by leaching with large amounts of water. Saline-sodic soils can be reclaimed using gypsum and leaching. A much better practice, however, is to avoid planting fruit trees on saline or saline-sodic soils.
Soil Organic Matter
The management of organic matter in soil is very important but sometimes misunderstood. Organic matter, as measured in soil tests, refers to chemically stable, invisible compounds, such as humic acids, that bind soil particles together. It does not refer to visible pieces of plant matter or manures.
As organic materials fall onto or are incorporated into the soil, they begin a complex process during which they break down and are changed physically and chemically. During this process, the organic matter provides food for micro- and macroorganisms in the soil, adds nutrients to the soil, and alters soil water-holding capacity and drainage. Chemicals are eventually formed from the organic residues and serve as glues that bind soil particles into larger clumps or aggregates. As the aggregates develop, open pore spaces also form in the soil. These pore spaces allow for the exchange of gases, facilitate root growth, and provide surfaces where roots can take up water and nutrients.
Sandy soils are inherently low in organic matter and respond slowly to programs designed to increase organic matter. In commercial Washington State orchards located on sandy soils, for example, soil organic matter may require 5 to 10 years to increase significantly after transition to organic practices. Forest soils and soils found in the American grasslands and Canadian Prairies often have naturally high concentrations of organic matter.
Measure organic matter before planting and every 2 years or so afterward to establish references or benchmarks. These benchmarks allow you to design soil-building programs and monitor the effects of your orchard management practices. Ideally, a new orchard site will have organic matter concentrations roughly between 3 and 5 percent, but do not be overly concerned if your site comes in higher or lower than that range.
Irrigation
Water is both a blessing and a curse for fruit growers. Trees obviously need water in order to survive, but excess water contributes to soil erosion, tree diseases, and generally poor fruit production.
The amount of irrigation water that you need depends on climate, soil, crop, tree size, and training practices. In the arid American West and parts of western Canada, frequent irrigation may be needed, particularly in orchards on light-textured (sandy) soils. In eastern North America, there is often less need for irrigation, and, indeed, you can often find domestic fruit trees growing wild with no irrigation. For optimum crop production and tree health, however, some irrigation is typically needed, even in high rainfall areas. Even short periods of drought stress during the growing season can reduce the number of fruits that develop and fruit size, as well as make trees more vulnerable to insect pests. Irrigation during the planting year is usually critical to getting your trees to survive and develop strong roots and tops.
Before investing in land or large amounts of planting stock and other establishment costs, estimate how much water you will need for irrigation during peak usage. It is difficult to make a general recommendation on the amount of irrigation water needed because it depends on many variables. If you are planning a large planting, your best strategy will be to consult local fruit growers, horticultural consultants, or university and governmental fruit specialists for their advice. In general, plan to replace the same amount of water that is lost due to evaporation as determined from evaporation pan measurements. In particularly arid regions you may need to increase irrigation for drought-sensitive crops.
Evaporation pans are simply round, metal pans. While at least two different designs exist, the U.S. National Weather Service uses Class A pans that are 47.5 inches in diameter and 10 inches deep. A hollow cylinder equipped with a metal needle in the center is used to mark a given water level. Each morning, enough water is added to restore the water level to that mark. The amount of water added is determined using a pitcher that is marked in hundredths of inches of water. That represents the amount of water lost by evaporation since the last filling. In agricultural areas, evaporation pan data is often available from the National Weather Service, a university, or various agricultural organizations.
Outside of these regions, evaporation pan data can be hard to locate. You might choose to install your own evaporation pan or to install any of several types of soil moisture monitoring devices, including vacuum tensiometers or soil moisture sensors and electronic meters. Inexpensive gypsum block sensors and handheld meters generally work well for orchard crops. Computerized systems are now available that monitor the soil moisture and transmit the data to your home or office computer. Some of these systems can be set to automatically turn on and off irrigation valves.
On my research farm, for example, we usually lost about 2 inches of water to evaporation each week during the warmest period of the summer, as measured with an evaporation pan. For the teaching orchard, we needed a source that provided 2 acre inches of water weekly during July and August.
Different types of irrigation systems use different amounts of water, so you will need to factor that in as well. Overhead sprinklers were once widely used in orchards, but they waste much water and increase diseases by wetting the foliage and fruit and increasing humidity within the canopy. If you intend to use sprinklers to control frost during bloom, plan to apply 1⁄4 inch of water each hour to your entire orchard for as long as temperatures are below freezing (see chapter 3 for more information on overhead sprinklers). Drip or trickle irrigation systems are very efficient in applying water directly to the tree roots and also keep the foliage and fruit dry. Drip systems do not, however, allow you to irrigate an alley crop and do not necessarily work well for in-row cover crops. How you choose to manage your orchard floor will influence how much water you need for irrigation.
For organic orchardists, microsprinklers provide a good compromise between overhead sprinklers and drip systems. You can irrigate your trees, alley crops, and cover crops at one time while keeping the canopy dry. Specially designed microsprinklers can also be used to provide frost protection, depending on the size of your trees.
Once you have determined how much water you need, ensure that you can legally access that amount of water at the times that you will need it. Water rights vary greatly from one area to another. Do not assume that you can access the surface water on or adjacent to your property, or use well water drawn from your property for irrigating an orchard. Also, determine how much it will cost you to access the water.
Identify surface waters and wetlands on and around your property. While they can be assets, they can also create legal problems. Depending on your location, national, state, and provincial environmental laws relating to wetlands and surface waters can limit what crops you grow on your property and what management practices you use.
Topography
Topography has a huge influence on where tree fruit crops are grown commercially. You may have noticed that the best commercial orchards are often located on slopes and benches above valley floors. Such sites generally offer good water drainage and allow cold, frosty air to flow away from the orchards. Fruit trees produce best in sunny locations, and a good site will provide full sun throughout the day.
Low-lying sites are often poorly suited to orchards. Water settles into low-lying areas, making drainage difficult. Cold air settles into depressions, called frost pockets, increasing frost damage to blossoms and developing fruits. Humid air is heavy and settles into the depressions, increasing the incidence of fruit tree diseases. Always select an orchard site that provides the best possible airflow and water drainage away from the site.
Be careful, however, when planting on steep slopes. While you can find orchards on very steep slopes, orchard operations become more difficult and dangerous and the risk of soil erosion increases. If you must plant on a steep slope, consider building terraces to create level planting areas. Figure 2.5 illustrates good and poor orchard sites.
Site History and Neighborhood
Before establishing an organic orchard, find out as much as you can about the previous use of the site. This step is especially important if you plan to become a certified organic grower because some previous activities can interfere with certification. Arsenic, lead, and mercury, for example, are highly toxic elements that were once widely used in agricultural pesticides, and so might have been used on old orchard sites. Unfortunately, they are also highly stable in the soil and persist for decades. If in doubt, have the soil tested before you plant.
Another reason to be wary of old orchard sites is the risk of replant disease. This problem is particularly serious when following apples with apples. Commercially, apple orchards have traditionally been fumigated prior to replanting to help kill several fungal pathogens that inhabit the soil and severely stunt new trees.
Replant disease is generally thought to be caused by a complex of several pathogens that probably vary from one region to another. Throughout the life of an orchard, these pathogens build up in the soil, although the established trees often remain healthy. When the old trees are removed and new trees planted, the new trees can die or remain stunted and unproductive. While conventional growers fumigate the soil with highly toxic chemicals (methyl bromide was once very popular for this purpose), soil fumigation is not available for organic growers. If you are considering a site on which old fruit trees were grown within the past few years, replant could become a serious issue, especially if you follow apples with apples. Some certified organic apple growers prefer to fumigate new planting blocks and go through a 3-year recertification in order to avoid replant problems.
Try to determine if your orchard site was ever used for businesses that could have contaminated the soil with toxic chemicals, including such activities as metal plating, battery recycling, or leather tanning. Again, if in doubt, have the soil tested for heavy metals.
Present-day activities near your farm can also interfere with your ability to grow fruit organically. Look around for abandoned or poorly cared-for orchards, which are often reservoirs of pests and diseases. Highly mobile pests, such as codling moth, Oriental fruit moth, apple maggot, and oblique-banded leaf roller, can be extremely difficult to control when there is a dense source of them nearby. The same caution applies to sites near to or surrounded by woodlots, hedgerows, or windbreaks where wild pome and stone fruits are abundant. Both native fruit species and escaped domestic species serve as reservoirs of diseases and pests and can make organic production challenging. The level of difficulty increases in smaller orchards. In large orchards, management programs can often trap pests within a few fruit tree rows around the perimeter, leaving the centers relatively free of pests.
Beware of industries that might pollute your site through contaminated air or surface water runoff. The same caution applies to adjacent, nonorganic farms, especially if their operations include airblast sprayers or aerial applications of pesticides. Growing organic orchard fruit can be challenging if you are near large acreages of cereal grain, corn, soybeans, cotton, or other crops for which crop duster planes and helicopters are still used to apply pesticides and herbicides.
Pests and Diseases
We will go into detail on pests and diseases in chapters 10 and 11. Pest and disease pressures are far lower in the American West and parts of western Canada than they are in more easterly locations. In eastern North America, for example, plum curculio is a pest that attacks many tree fruit crops and has long been one of the most serious challenges for organic fruit growers. Apple scab, brown blight on stone fruits, and other fungal and bacterial pathogens are also more common and severe in the humid East.
As far as regions go, you should not let potential pest and disease problems be the deciding factor on whether to grow fruit organically. New fruit varieties, more effective organic pesticides, and improved cultural practices allow you to grow organically, regardless of your location.
Access and Utilities
For commercial growers, transportation is a critical factor. You need to be able to get equipment, supplies, and workers into and out of your orchard easily, safely, and economically. Research also shows that much of the bruising and loss of quality to apples and other tree fruits occurs during transportation from the orchard to the packing house or other market outlet. Rough roads are a prime culprit, along with rough-riding trucks and other transportation equipment. Dust from dirt roads adjacent to orchards can contaminate fruits, requiring additional cleaning and handling to prepare them for market.
Wherever possible, paved roads offer a cleaner and smoother alternative to dirt or gravel roads. Paved roads may also mean being close to a population center or on a heavily traveled highway (think customers). If you must farm where paved roads are unavailable, try to select locations where the unpaved roads are well maintained and dust abatement programs are used.
You may also want to consider your proximity to other growers. While having your orchard be unique to an area may give you marketing advantages through lack of competition, you also face disadvantages. Those disadvantages increase with the size of your orchard. In established fruit growing regions, growers typically form cooperatives that enable them to collectively bargain with vendors for reduced rates on supplies and equipment. Cooperatives can also provide for sharing occasionally used, high-cost equipment, and for sharing farm workers. Food cooperatives can be excellent markets for your fruit. Such cooperatives may be hard to find in regions with few fruit growers.
Areas where organic fruit production is widespread also offer educational advantages. Organic orchardists in Washington and California, for example, enjoy abundant technical support from state universities, Cooperative Extension educators and specialists, private crop consultants, and analytical laboratories. In areas where organic fruit production has not become widely established, technical support will be more limited and not necessarily of the best quality.
Your orchard operation may or may not require utilities, including electrical power, natural gas, telephone, and Internet. Develop a production and marketing plan before you start looking for an orchard site. If you plan to transport all of the fruit to a packing house or other outlet, you may not need utilities. If you are planning to store your fruit on site or process it there, you are likely to need some utilities for refrigeration, lighting, heating, and other operations. Before investing in an orchard site, determine if the needed utilities are available and what their costs will be.
Labor and the Law
Producing tree fruits is labor-intensive. Pruning, thinning, managing vegetation, controlling pests and diseases, and harvesting are the most labor-intensive operations. For a home or small market orchard, labor can usually be handled by the owner, the family, or a few employees. Large orchards, however, usually require much seasonal labor.
Before investing in an orchard site or establishment, be sure that you have a sufficient pool of laborers willing to work in your orchard at the times you need them and at wages you can afford. One advantage organic growers have over conventional growers is that potential employees often prefer to work in orchards free of toxic chemicals.
Depending on your area and goals, you may have to consider legal constraints to developing and setting up your orchard. For a home orchard, this is seldom an issue, although some subdivisions, even in rural areas, have covenants and restrictions that can interfere with establishing an orchard. Before starting a commercial enterprise, be sure that you will be allowed to grow and market your fruit where and how you want. Some counties, for example, severely limit where roadside stands can be placed and what can be sold. Zoning laws can help or hinder you. Before investing in a commercial orchard, thoroughly check out local and state laws and regulations that will pertain to organic fruit production.
