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Protocol Information

Roy Laframboise and Rodney Wahl
Towner State Nursery
HC 2, Box 13
Towner, North Dakota 58788

Family Scientific Name: Fagaceae
Family Common Name: Oak family
Scientific Name: Quercus macrocarpa (Michx.)
Common Name: Bur oak
Species Code: QUEMAC
Ecotype: North Dakota , Northern Great Plains
General Distribution: Q. macrocarpa grows from New Brunswick west to Manitoba, south to eastern Texas, northeast to Tennessee, West Virginia, and New York.
Propagation Goal: Plants
Propagation Method: Seed
Product Type: Container (plug)
Stock Type: 1+0 container seedling
Time To Grow: 12 Months
Target Specifications: Height: 20 to 27 cm
Caliper: 4 to 6 mm
Root System: Firm root plug
Propagule Collection: Collected by hand from Turtle Mountains, ND.
Propagule Processing: Seed is extracted by removal of loose cups, twigs and other debris. Sorting and cleaning can by done by flotation or hand.
Pre-Planting Treatments: Float test acorns in water and use only sinkers. Place wet acorns in a plastic bag in a refrigerator for 135 days of cold, moist stratification at 0 to 2 °C (32 to 36 °F). Move to greenhouse and spread out acorns on a wire mesh tray and cover with wet burlap and keep moist until germination is completed.
Growing Area Preparation/
Annual Practices for Perennial Crops:

Propagation Environment: Fully-controlled greenhouse.
Propagation Method: Seeds. Sowing germinants.
Container Type and Volume: Bur oak requires a large container to accommodate the large acorn and that is also widely spaced to permit good caliper development. The Spencer- Lemaire Tinus Rootrainer® has a top opening of 3.8 x 5.1 cm and is 18.5 cm deep (1.5 x 2 x 7.2 in.). The cavities are 350 cm3 (21.5 in3) in volume with a cell density of 516 cells/m2(48/ft2).
Growing Media: 50% Sphagnum peat moss and 50% #2 grade vermiculite. Fill cavities and tamp lightly to remove air pockets. Use a large pointed dibble board to make room for the germinating seeds. Sowing/Planting Technique: Remove germinating acorns and place one germinant in each container. Be sure to orient the radicle downwards to prevent abnormal stem crooking. Cover germinants with a shallow layer of perlite.
Establishment Phase: Keep the greenhouse warm and humid both day and night. Frequent misting is all that is needed to keep the media moist, but no wet until the primary leaves have developed. Fertigate with a low nitrogen (100 ppm) but well-balanced fertilizer solution twice per week. Keep leaves dry to avoid fungal pathogens. Bur oak seedlings can tolerate full sunlight so shading is not necessary. Photoperiodic lighting is required to keep the seedlings actively growing. Turn on the carbon dioxide generators as soon as the primary leaves develop and set it to come on about 4 hours before sunrise.
Length of Establishment Phase: 2 months
Active Growth Phase: After the seedlings are well established in the container, the day temperature range can be increased to 24 °C (75 °F) to 32 °C (90 °F) to promote multiple flushing. Bur oak grows in a series of up to 4 flushes of about the same amount. The relative humidity should also be kept high to minimize moisture stress. As the leaves increase in size, irrigation will become more difficult because a high percentage of the applied water is intercepted and never makes it into the growing medium. Therefore, the duration of each irrigation and the number of irrigations per week must be increased accordingly. Although it is simplest to wait to irrigate until the foliage begins to wilt, monitoring the weight of the containers is the easiest way to keep the growing medium in the ideal moisture range. Fertigate with a high nitrogen (150 ppm) but well-balanced fertilizer solution twice per week to keep all essential mineral nutrients at optimum levels.
Length of Active Growth Phase: 4 months
Hardening Phase: Seedlings that have reached 80% of target height are moved to the shadehouse in mid-August for hardening under ambient conditions. The seedlings should be placed on raised benches to continue encouraging air pruning of the roots. The change to lower humidity and natural photoperiod will help trigger the hardening process but you should switch to a hardening fertilizer formula with a reduced nitrogen level of around 50 ppm. This should be applied as long as day temperatures are above freezing and the root plugs remain unfrozen.
Length of Hardening Phase: 8 weeks
Harvesting, Storage and Shipping: Total time to Harvest: 12 months
Harvest Date: April 1 or as weather on outplanting site allows.
Storage Conditions: Move container onto the ground and pack tightly with a perimeter covering of sawdust to protect the roots from repeated freezing and rethawing. Protect from rodent and animal predation by using bait stations and keeping the shadehouse completely enclosed.
Length of Storage: : The oak seedlings will remain dormant as long as
References: Seeds of Woody Plants of the United States, USFS, USDA, Agriculture Handbook #450, 1974.

Laframboise, Roy; Wahl, Rodney. 2001. Propagation protocol for production of container Quercus macrocarpa (Michx.) plants (1+0 container seedling); Towner State Nursery , Towner, North Dakota. In: Native Plant Network. URL: http://www.nativeplantnetwork.org (accessed 27 August 2015). Moscow (ID): University of Idaho, College of Natural Resources, Forest Research Nursery.