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Protocol Information

Jennifer Kleffner
Former Nursery Director
Lower Colorado River Prop. Specialist
PO Box 666
Bayfield, Colorado 81122
970/884/8191
jkleffner@hotmail.com


Family Scientific Name: Salicaceae
Family Common Name: Willow
Scientific Name: Populus fremontii S. Wats fremontii
Common Name: Fremont Cottonwood
General Distribution: Southwestern New Mexico westward through Arizona and California, extending north into southern and western Nevada, and southern and eastern Utah. Note that Fremont Cottonwood does not occur in Colorado. The Colorado species, which looks similar, is the Rio Grand Cottonwood (Populus deltoides var. wislizeni).
Propagation Goal: Plants
Propagation Method: Vegetative
Product Type: Container (plug)
Stock Type: 1 gallon
Time To Grow: 4 Months
Target Specifications: From whip plantings, tree should have an established root system and be leafed out and actively growing.
Propagule Collection: Cottonwoods are best rooted from semi-hardwood cuttings of the current season's growth. Ideally, an equal percentage of male and female cuttings are taken, but this is sometimes difficult to determine unless you have seen the tree while in bloom. Be aware that many 'landscape' cottonwoods are purposely male, to avoid the mess of the female seed fluff. Prune lower side shoots (whips) with base measurements of at least one inch from larger trees. Cuttings can be taken at any time, but the best times are either as the tree is going dormant in the late fall (November) or when it is actively growing (June/July). Poles can be anywhere from ½ inch in diameter and up, but seem to do best when measuring about 1 inch across.
Propagule Processing: Hold whips in water tanks, cut side submerged. Do not let cut ends dry out. If they do, recut. Remove side shoots and cut whips down to about 10-12 inches long, cutting between nodes and discarding ends as they get too small (about as big around as your pinky finger).
Pre-Planting Treatments: Cut poles can be held in water tanks for up to a week with no ill effects. Treat with .1% IBA (rooting hormone) for higher rooting percentages and faster root development. While this may not be completely necessary, I've never wanted to risk it.
Growing Area Preparation/
Annual Practices for Perennial Crops:

All plants in our nursery are grown outside under 68% shade cloth or in full sun. (Plants grown under shade will be more leggy, but soil temperatures will be lower during the summer heat. Its a trade off.) Therefore, outside temperature dictates when to plant. Pots are the typical 7 in diameter x 7 in high black plastic pots such as the ones made by Nursery Supply. However, we reuse and buy back pots, so they are often a mix of slightly different sizes, styles and brands. No additional cleaning is done. Soil mixture is approximately 50% local soil (sand) and 50% inexpensive wood mulch (mostly to lighten up the pots for shipping)
Establishment Phase: Push each pole into a one gallon pot so that half of the pole is covered with soil. Firm soil around pole to ensure continuous soil contact and keep soil very moist. Winter cuttings are easier as the pots are less likely to dry out between watering. Plant 20% over number needed to allow for some unrooted cuttings. We fertilize with Best-Tab slow release 20-10-5 fertilizer, one per pot, at time of planting.
Length of Establishment Phase: rooting-3 weeks, leaf out-one to two months
Active Growth Phase: Cuttings will start to root within three weeks. Leaves will begin to emerge when trees normally break dormancy, or within two weeks for summer cuttings. There are many different phenotypes of Fremont Cottonwood in the SW Arizona area, and depending upon the water shed in which they evolved, they bloom anytime from February to July. The leaf out is also staggered accordingly.
Length of Active Growth Phase: 4 months.
Hardening Phase: Whips planted in November/December will be ready for outplanting by mid April. Trees can be held over for up to a year if necessary, as long as they continue to receive adequate water. However, they do become quite rootbound, and have a tendency to root out of the bottom of the pot.
Length of Hardening Phase: None
Harvesting, Storage and Shipping: Plants are hand loaded onto trucks and delivered to the outplanting site. Care is taken to ensure that trees do not dry out during this critical move, watering right before loading and right after unloading.
Length of Storage: None.
Outplanting performance on typical sites: The best time to outplant is in April. The later the time of year, the hotter it is and the harder it is to keep the trees from drying out. Cottonwoods are very water loving, and must have supplemental water until the roots reach the water table. If the water table is too deep, (over eight feet) the trees will need supplemental water in perpetuity.
Other Comments: Many cottonwood/willow revegetation plantings are short sighted and fail within the first five years. Do your homework before planting. Determine distance to water table, soil salinity, and ability to maintain the site. Ideally, don't plant everything the first year, creating an artificial even aged stand. Interplant with other riparian species to create a multi layered diverse habitat.
References: For information on ongoing cottonwood/willow revegetation projects, contact Cibola and Imperial National Wildlife Refuges in Arizona, the Bosque del Apache National Wildlife Refuge in New Mexico, and refer to research by Julie Stromberg of Arizona State University on the Nature Conservancy Hassayampa River Preserve in Arizona. Also, much restoration work has been done by Dr. Bertin Anderson of Revegetation and Wildlife Management in Blythe California. (760) 922-2541. Dr. Anderson has been doing work in the Southwest for over 20 years, and while sometimes a bit prickly to deal with, is well worth knowing. Read his papers first.

Citation:
Kleffner, Jennifer 2001. Propagation protocol for vegetative production of container Populus fremontii S. Wats fremontii plants (1 gallon); Lower Colorado River Prop. Specialist, Bayfield, Colorado. In: Native Plant Network. URL: http://www.nativeplantnetwork.org (accessed 22 September 2014). Moscow (ID): University of Idaho, College of Natural Resources, Forest Research Nursery.