Proper early care of young trees is pivotal to the long-term health and success of your orchard as it matures. Young trees are more susceptible to pests, diseases, and competition from other vegetation when they are young. Taking simple steps to protecting your trees from drought, sunscald, fire blight, and weed competition will protect your investment for years to come. For general information about caring for young trees, listen to the workshop presentation Site Preparation, Tree Planting, and Early Care.

Proper care and maintenance

The first step to protecting trees is to make sure they are getting the essential resources they need to grow and mature. Make sure before you even start planting that you have adequate water and your irrigation is set up to provide young trees with 1 to 2 gallons of water per day during the peak growing season. Overwatering can also lead to issues, so be sure that your trees are getting just what they need — no more, no less.

Depending on your soil quality and pre-planting amendments, your trees may need some additional fertilizer, however this should be applied carefully so as to not encourage too much vigor. Fertilizer recommendations vary depending on the circumstance but the goal is terminal growth of about 10 to 24 inches. Over-fertilizing young trees may leave them susceptible to cold injury and fire blight. If a soil or foliar test indicates that young trees need more Nitrogen, apply it early in May and June and spread out applications, especially if soils are coarse. Do not apply fertilizer late in the growing season, as this can result in delayed dormancy leaving trees susceptible to winter injury. For more information on fertilizing young apple trees, refer to the Ontario Ministry of Agriculture, Food and Rural Affairs publication Fertilizing the New Apple Orchard.

Weeds

When trees are young and roots systems are still developing, they are particularly susceptible to competition from weeds for water and nutrients. Keeping a 2- to 6-foot vegetation-free buffer around trees will reduce this competition and allow trees to more freely find the water and soil nutrients they need to grow and fight off pests and diseases. In addition, keeping vegetation low and away from young trunks reduces opportunities for browsing by rodents, which can girdle trees and feed on roots. 

The first step to controlling your weeds is to know what weeds you have and therefore understand their life cycle and options for controlling them. Several services exist if you are unsure, including your county Weed District or Extension Office, which can be a helpful resource in identifying weeds as well as controlling them. You can also find resources for identifying mature weeds through the Montana Weed Control Council, and weed seedlings with the MSU Weed Seedling Identification Guide. Once weeds have been identified as annuals, biennials, or perennials, a strategic weed control plan can be devised. Research from New York orchards has shown that controlling weeds early and consistently through the growing season (May-July) results in more tree growth and fruit yield then if control is limited or delayed as weeds mature (Merwin and Ray, 1997). 

For more information on controlling weeds in young orchards, listen to the the workshop presentation Site Preparation, Tree Planting and Early Care or visit WSU Weed Control webpage. Remember, it is important to only use labeled products and follow the label for rates, application timing, and other instructions to ensure safe and effective use.

Winter Injury and Sunscald

Montana's fluctuating daily and seasonal temperatures can be hard on trees. Sudden changes in temperature, particularly in the fall and winter, can leave trees vulnerable to winter injury as they are either yet to reach dormancy or break it after extended warm temperatures too early in the season. Winter injury can result in bud injury, limb or terminal death, secondary infection from pathogens like cystospora and leave trees vulnerable to other pests such as flat-headed borers. The first step to protecting trees is to plant cold hardy varieties appropriate for your USDA Cold Hardiness Zone. Growers can also encourage trees to go dormant by reducing water in late summer to early fall and avoid fertilizing or pruning trees too late in the season.

Additionally, all young trees should be painted with white latex paint below the first limb to prevent sunscald. This can easily be done with a gloved hand, cloth and paint diluted with water. Sunscald is caused when tree cells are warmed on sunny winter days and break dormancy.  As temperatures cool in the evening cells are damaged leaving trees vulnerable to secondary infections, pests and tissue death girdling the tree. 

For more information on understanding tree dormancy, identifying winter injury, and how to manage it, check out these resources:

Clements, Jon. 2014. Cold Injury in Fruit Trees. Presented at Ontario Fruit and Vegetable Conference February 2014.

Growing Produce, "Time to Check Your Crops for Winter Injury." March 4, 2014.

OMAFRA, "Winter Injury and Apple Cankers." April 2014.

Schmelzer, Lee. "Abiotic Winter Damage." Montana State University.

Fire blight

Young trees are particularly vulnerable to fire blight as they are small and growing rapidly, allowing the disease to more quickly and easily spread to the trunk and rootstock, potenially killing the whole tree. While some apple cultivars and rootstocks have some resistence to the disease, many heirloom varieties and cider apple cultivars have demonstrated susceptibility in Montana plantings. Preventative steps should be taken early on to prevent infection from fire blight, which is spread by pollinators via blossoms in the spring. What level of defense growers use will depend on the age of trees, their susceptibility to fire blight, and if the orchard was infected in previous years or if neighboring trees show signs of potential infection.  

For more information on preventing fire blight, refer to the following resources:

- MSU Apple Grower Workshop presentations:

- Site Preparation, Tree Planting and Early Care

- Fire blight in Montana

- WSU Tree Fruit Fire Blight

Wildlife

While large browsers such as deer and elk can be excluded from the orchard with a well-designed fence, smaller animals such as pocket gophers, voles, and ground squirrels can easily breach fencing and gain access to your young orchard. Controlling these pests early on is an important step in making sure they are not left to completely girdle young trees or destroy their roots. While the life cycle of these pests can make them difficult to control completely, there are certain steps that can be taken to limit their damage. For more information on Integrated Pest Management of rodents in orchards, refer to the section "Rodent Management" in the Intermountain Tree Fruit Production Guide.