A. SITE SELECTION

In deciding whether or not to develop a site for wild blueberry production, it is advisable to analyze the factors which can influence its productivity and profitability. Whether the choice between several sites is available or not, this exercise is always worthwhile.

The main points to consider in site selection are:

The Degree of Wild Blueberry Plant Cover

The quantity and distribution of wild blueberry plants on a site is by far the most important consideration in site selection. An ideal site will have plants distributed throughout the site and a good density within each spot. Plant cover refers to the proportion of the field which has wild blueberry plants in it, while plant density refers to the number of stems per surface area (e.g., 10 stems/.09 m²). A minimum of 50% plant cover is acceptable, but 75% cover will be required to achieve profitability in a short period of time. Through good management, it is much easier to increase the plant density than it is to increase the plant cover.

The Dominant Plants

This refers to the species of plants which are growing on the site. Several situations are possible.

• An abandoned hayfield with a strong cover of wild blueberry plants is the ideal situation. The clearing and levelling costs are negligible, in comparison to other situations. In addition, wild blueberry fields developed from farm land tend to have more fertile soils, and less sour-top (the taller, more hairy species of wild blueberries) than fields developed from woodlands. The presence of sour-top can lower yields, because its pollen is incompatible with that of the sweet-top blueberry.
• In a mature forest stand, the clearing and cleaning work is enormous, but the sale of wood may help to defray some or all of the costs. A significant disadvantage is the cost associated with stump removal. Furthermore, it is preferable that stump removal not be performed for a couple of cycles after clearing. This, in turn, will increase the time needed to mechanize operations.
• In a forest stand composed of young and mature trees, the costs associated with clearing will definitely be superior to the revenue from the sale of the wood. It is important to consider the additional costs before developing this type of site.
• In a site developed from hardwood forest, the herbicide costs associated with strong regrowth can be anticipated. In addition, stump removal is generally more costly with hardwoods than with conifers. On the other hand, hardwood forests tend to have more fertile soils, which generally have higher yield potentials.
• When the site consists mainly of brush (after a cut or a forest fire), it is easier to clear the site using mechanical implements. Many fields have been developed from these conditions.

The Physical Conditions of the Site

The physical characteristics to consider are:

• The presence or absence of rocks (boulders, stones, rocks and ledge) is an important consideration. The presence of large quantities of medium-sized rocks can make the field much more costly to level than a few conspicuous boulders.
• The roughness of the field is important, since it may be costly and destructive to level.
• The topography of the field is significant, since the slope may have an impact on the ability to mechanize, and may make the field subject to erosion and pesticide/ fertilizer leaching or runoff.
• The presence of stumps will slow the ability to mechanize and will incur a cost for removal.

Air Drainage

Natural air drainage is desirable in order to minimize the danger of spring frosts due to stagnant air pockets or cold air accumulations in low-lying areas. If there is no way to modify the terrain for evacuation of this air, then the site should be avoided.

Soil Drainage

Soils which hold surface water for relatively long periods of time should be avoided, unless the site can be improved economically by surface or sub-surface drainage. A poorly drained site will cause a delay in field operations in the spring because of the hindrance to heavy machinery. Unless field operations can be performed in the fall, or by hand in the spring, these sites should be avoided.

Soil Quality

Wild blueberries do not need deep soils to grow -15 to 20 cm is adequate. However, if the soil, including the organic matter layer, is too thin, the productivity of the crop will be lower. The organic matter layer should be at least 1 cm deep.

Wild blueberry crops can be produced from a wide range of soil fertility levels. Sites are generally more productive if the soil fertility is relatively high and the pH is between 4.5 - 5.5. Soils of agricultural origin, in which the organic matter layer has been mixed with the soil, tend to be more productive than soils of forest origin. It is thought the organic matter in the old agricultural fields has a better capacity to "work".

Types of Weeds

It is a good idea to evaluate the weeds present in a potential field, in order to ensure that these can be controlled adequately. It is preferable to avoid sites or sections of fields which are infested with weeds that are difficult to control (e.g., bunchberry and mountain holly).

Field Access

It is essential to have guaranteed access to a site at all times, in order to:

• execute field operations at the right time;
• get pickers to the field relatively easily;
• scout the field for insects and diseases; and
• have quick access in case of forest fires.

Proximity of Residential Communities

The use of pesticides is increasingly controversial. It is therefore important to consider environmental impacts (either real or perceived), in order to ensure that field operations will not antagonize neighbouring communities (e.g., water contamination, drift from pesticides, fire and smoke).

Proximity of Water Courses and Wells

During site development, it is important to consider the proximity of water courses and to respect the buffer zone legislated between agricultural fields and water courses.

B. SITE DEVELOPMENT

Developing a wild blueberry field consists of felling and clearing all the trees and shrubs in order to begin production. Debris can be burned in the bare areas of fields or in the fire-breaks. Burning piles on top of wild blueberry patches should be avoided, because the intense heat will damage the plants' rhizomes. The plants may take years to recover, if at all, and the loss of productivity may be superior to the cost of removing the debris. The most efficient way to clear is to create windrows while felling and to remove the windrowed debris after. The limbs may be chipped, and the woodchips will eventually decompose and improve the fertility and water retention of the site.

During tree felling, the stumps should be cut flush with the soil, so that they do not interfere with the other activities necessary for field development. It is a good idea to retain rows of trees and/or shrubs at regular intervals in the fields. These rows will act as windbreaks and the wind reduction will favour snow accumulation and pollination. For more details on windbreaks, please refer to factsheet A.4.0.

Lastly, a fire-break should be created at the field's periphery in order to block the flow of run-away fires during burning. These fire-breaks must meet the requirements of the Department of Natural Resources and Energy. Factsheet A.10.0 defines these requirements.

Prepared by Gaétan Chiasson, P.Ag. Horticulturlal Specialist , and John Argall, P.Ag., Blueberry Specialist, N.B. Department of Agriculture & Rural Development

Fall 1995