Historically, experts have recommended root pruning after nursery stock is dormant, a practice that develops a more concentrated root system and thereby enhances transplant survival. However, in areas of North Carolina with rocky and heavy clay soils, root pruning is difficult or nearly impossible without very specialized equipment. Current research suggests that drip irrigation encourages roots to grow to the standard root ball size and allows harvesting the majority of the root system when digging.
A factor frequently forgotten in nursery stock production is the weight of the root ball. Transporting plants that weigh more than 50 pounds each without mechanical assistance is time consuming, expensive, bad for employee morale, and may result in worker’s compensation claims. Examples of the size of rootballs required for coniferous evergreens, and the resulting soil weights are shown in Table 3.
Ground cover within a field nursery is essential to minimize soil losses and maintain long-term soil productivity. In addition, a well-established sod makes it easier to drive through fields when they are muddy or covered in snow or ice. A well-established sod is frequently the only economical way to support equipment such as tractors, sprayers, or mechanical harvesters when the soil is wet. Furthermore, research has demonstrated the need for a vegetative barrier around the edges of a field nursery. Grassed contour strips slow down and direct flow of water across a slope and serve as a buffer and final biological filter to remove any excess nutrients before runoff leaves the nursery. Tall fescue, orchardgrass, and bermudagrass are effective in providing workable sod because they are vigorous and provide a great deal of biomass.
If improperly managed, however, ground covers can compete with nursery crops for fertilizer, light, and water, thereby reducing crop growth. A common way to minimize competition while enjoying the advantages of a ground cover is to keep the rows clean or mostly weed free with preemergence or postemergence herbicides while maintaining a ground cover in the middles between the rows.
To reduce the cost of mowing, sub-lethal rates of herbicides (referred to as chemical mowing) and/or growth regulators can be used to slow growth of grass but not kill it. For example, spraying tall fescue or orchard grass in early spring when there are four to five new leaves or seven to ten days after mowing with 1 pint / acre of sethoxydim (Vantage), a selective grass herbicide, will suppress the grass for eight to ten weeks. Another alternative is glyphosate (Roundup 4L) at the rate of 4 to 8 ounces per acre as a directed spray. The 4-ounce rate usually gives six weeks of suppression; the 8-ounce rate gives about 10 weeks of suppression at a cost of a couple of dollars per acre, much less than regular mowing. Glyphosate needs to be applied as a directed spray between the nursery stock rows. Use no more than 25 gallons of the final spray mix per broadcast acre. Chemical mowing will result in chlorotic (yellow) grass for up to 30 days. Common preemergent herbicides labeled for field production are listed in Table 4.
| Winter Pruning | Postmergence | ||||||||||||||||||||||||||||||||||||||
| Index | |||||||||||||||||||||||||||||||||||||||