~Weed Management~

The class I am taking towards my horticulture certificate right now is Weed Management. For our second assignment (which was somewhat fun to do involved creating a weed management plan for a new apple orchard in the Okanagan Valley. Thought that I would post to share.

Laura’s Orchard was purchased as an abandoned farm field in the Okanagan Valley in British Columbia Canada. The near perfect fruit growing climate of the valley is hoping to prove beneficial to a successful apple orchard. As the land was an abandoned farm field, it has been found overrun with weeds. In order to establish the orchard, a three year establishment and maintenance plan has been put together to cultivate an operating orchard. Prior to purchase a soil analysis was completed to establish the condition of the existing soil, and was found that the OM level is 3.5 and the pH level is 7.2. Ideally, apple orchards have a pH level of 6-6.5 however through discussions with other orchard owners in the area – it was found that a pH of 7.2 is fine for apples, and that they typically do well. The sandy loam soil provides great drainage for apples. Essentially, once the weeds are controlled , ideal conditions will be available for the orchard.

Year One – Pre-Planting Year

As the land needs to be cleared of weeds, and the orchard is not yet an established, it is much easier to manage and get rid of the weeds prior to giving them ample opportunity to grow. As researched, I have found that the perennials we are dealing with (Canada thistle, perennial sow thistle and field bindweed) have strong root systems and may cause problems when tillage is used. Ideally, we don’t want more weeds growing from the cut roots, so for the first year, the plan is not to perform any tillage till the fall.
Once the ground is workable, and weeds have started to grow, a burn-off (Round-Up) will occur as there are no trees to worry about burning. Once the burn-off is complete killing off the weed vegetation, a cover crop will be planted to help control the annual & perennial weeds, in addition to adding organic matter to the soil. Mow downs of the field as a whole will occur often throughout the season to ensure any annual weeds are maintained. Additional applications of the residual herbicide will be applied as required (typically when the weeds are flowering).
Timing is very important throughout the first year as we need to ensure we get the weeds at the right time, spraying will occur as required with additional selective herbicides. During the early fall, tillage will occur to work the soil, and a cover crop of Sundan x sorghum will be planted to add some organic matter to the soil. The Sundan X sorghum cross will be mowed down as much as required to ensure weeds do not flower. Although we cannot expect to be free of the perennial weeds in one season, hopefully we have gained a reasonable amount of control with the methods above.
A glyphosate herbicide has been chosen for the majority of the orchard as it has been found to be safe for bees, and water run-off.

Year Two – Planting Year

The orchard will be laid out in a North South direction for optimal sunlight. As planting will be occurring the late fall or early winter (best done when the trees are dormant) we have additional time to manage weeds, preparation of the soil and install irrigation.
In the early spring the land will be tilled, and laid out. Orchard sod (fescue) will be placed down between the tree rows, this will help prevent some weeds from growing through in addition to fighting erosion. Tree strips will be managed with herbicides to ensure as much of a weed free environment as possible for the new plants. Once the rows are laid out, the irrigation systems will be installed and flagged. A trickle irrigation system will be used, as many apple trees prefer this method of watering. The planting strips will be monitored for weed growth throughout the season. Mow downs will occur, and selective sprays of herbicides will be completed as the orchard requires. Ideally, we would like to have the orchard weed free prior to late fall for planting, economic considerations may require a management plan of the remaining weeds.
Apple trees will be purchased in the late summer. The orchard will be purchasing two year old (strong stems and side branches) dwarf trees as they mature and produce fruit faster then non-dwarf trees in addition to being able to planted much more densely. Harvesting in another factor taken into consideration when choosing trees, apples can be harvested from the ground, should the opportunity of a pick-your own orchard be chosen. The dwarf trees are also easier to spray and maintain. The cost of the dwarf trees is much higher than larger trees, however, the greater yield outweighs the initial expensive investment. Research has shown that two varieties of apples grown in the same orchard is required for successful pollination. For our orchard we have chosen the Gala and Ambrosia varieties.
During the summer and early fall, the midsections will be mowed for control, the tree strips will be managed mechanically and by hand to ensure the weeds are managed as best as possible.
Planting in late fall will occur, this will be done when the trees are dormant, ideally the remaining weeds will not compete with the root system as heavily. When digging the tree pits, they will be dug deep, the topsoil will be saved after it has been sifted through for weeds, and the subsoil will be disposed of. A non-residual herbicide will be applied at this time to help control the weeds. A mulch of grass clippings from the sod rows and non-dyed newspaper will be placed in the tree rows leaving a 25-30cm around each tree trunk and a tree guard to help prevent damage from rodents.

Year 3 – Maintenance

In the spring of the third year, a 10-52-10 fertilizer will be added to the trees to encourage root growth. A residual herbicide for new plantings will be applied, and research has shown that you should receive eight to twelve weeks of control with this spray. Mow downs when the annual weeds have reared their heads will occur. In the early summer, another application of herbicide (selective) will be required on the orchard sod to help prevent more weeds for growing. The tree rows will require hand hoeing/cultivation due to the delicate nature of the new growth.
In the early summer, the bee hives will be brought in, two to three hives per hectare to ensure proper pollination – each bloom requires about 24 bee visits for proper pollination. Throughout the growing period (summer) mow downs will occur in addition to very specific herbicide application. Due to the sensitive nature of the trees, a directional sprayer will be used. This will be beneficial at controlling the perennial weeds.
Once all the usable fruit has been removed in the fall, an additional fall application of Round-Up will occur, to help again to maintain the perennial weeds. Hopefully within a couple of growing seasons, the perennials will no longer be a problem.
Since much control and eradication procedures have been focused on throughout the first three establishment years, continued supervision and regular monitoring of the weed conditions should allow for solutions prior to having additional problems develop.