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Tips for Producing Phylloxera-resistant Grafted Vines

Additional Fact Sheets on Phylloxera:

Contributing List of Authors: Ed Hellman. Oregon State University. This fact sheet and others on grape phylloxera were produced as a set by a phylloxera task force at Oregon State University: Bernadine Strik, Extension Berry Crops Specialist; M. Carmo Candolfi-Vasconcelos, Extension Viticulture Specialist; Glenn Fisher, Extension Entomologist; Edward Hellman, Extension Horticulture Agent; Steven Price, Post-doctoral Research Associate, viticulture; Anne Connelly, Master’s student, horticulture; and Paula Stonerod, Research Aide, horticulture. The authors of this fact sheet acknowledge the help and guidance of others on this task force.

Planting winegrape plants grafted to phylloxera-resistant rootstocks is the only sure way to avoid phylloxera damage to a vineyard. Grafted plants are expensive, however (five or six times the cost of self-rooted cuttings). You can reduce the cost of replanting if you produce your own grafted plants. Bench grafting is a relatively simple process, but there are several key points that can greatly affect your success.

The following system has been used by some Oregon growers with good results. It is a modification of a commercial system used in New Zealand by several nurseries and appears to work well there on all of the standard rootstocks. Unlike traditional methods, it does not require an 80oF callusing room or a greenhouse, making it an appealing system for small-scale grafting operations.

Rootstock wood is first cut to length (12 to 16″) and disbudded. You can disbud rootstock wood at the time of collection with a pruner, or later using a wire brush on a bench grinder. All wood for grafting must be stored under cool, moist conditions prior to use to avoid desiccation. Single-node scions for grafting should be carefully selected to match the size of the rootstock. Grafts can be made by hand, using a whip and tongue graft for example, but they are easiest when done with a grafting machine that makes either an omega, slot, or “V” cut. The graft union is secured with a 1″ wrap of plastic electrician’s tape. The graft union and the bud are then dipped in melted wax (a mix of equal parts beeswax, paraffin, and linseed oil) and then in cold water. Make sure the wax is not too hot–keep it just above the melting point.

Callusing is done in a waterproof container at least 18″ high. A range of containers are used in New Zealand, from waxed lettuce boxes with their sides taped up to 4′ x 4′ plastic picking bins. The container should be filled with 9″ of moist perlite, with the grafted cuttings placed in the container right-side-up! The graft union should be several inches above the perlite. Seal the whole container with transparent plastic to keep the air in the container at 100% humidity. Keep the temperature inside the box at 80oF. Be sure to monitor the temperature both in the air, under the plastic, and in the perlite. Lights should be suspended over the containers. The light source is not important–banks of fluorescent lights, quartz work lights, or incandescent bulbs all work fine. Usually the lights supply all the heat necessary. The temperature in the container can be adjusted by raising or lowering the lights. Some rootstocks may require bottom heat to improve rooting, but this is probably not necessary with most of the common rootstocks being considered in Oregon.

After three to five weeks, when new shoots on the scion are about one inch long, the grafted cuttings are removed from the boxes. If there are longer shoots, they can be trimmed to two nodes and the larger leaves removed. The top of the cutting is again dipped, either in wax (this time a mix of equal parts beeswax and linseed oil) or a plastic anti-transpirant. If you use wax, keep the temperature cooler than the first dip and dip the grafted cutting in cold water after the wax dip.

After callusing, you can plant the grafted cuttings directly in the nursery. Cover well-worked soil with 3′-wide black plastic strips two weeks before planting to warm the soil. Just prior to planting, run a spiked wheel, or some other device, over the plastic to mark the spacing and cut holes in the plastic. Space cuttings four to six inches apart, with two rows of cuttings on each plastic sheet. Dig plants the following dormant season.

Timing of the whole operation depends on the planting date in the nursery. To plant cuttings in warm soil in mid- to late-May, graft in early- to mid-April. Typical success rates in New Zealand average around 55% take. At Oregon State University, we have had success rates of 40 to 70%, depending on the rootstock. The one rather noticeable exception was 1616, where we had no take. Some Oregon growers have had 90% success using this system. The plant quality after growth in the nursery is generally very good, with large root systems and adequate top growth.

The quality of nursery stock you produce will be closely tied to your nursery practices. Generally, the best nursery ground is not the best ground for vineyards. Nurseries should be planted on rich, fertile soil that is easily dug in the winter. A sandy loam is considered ideal. Make sure the plants are well watered and fertilized during the growing season.

This method is a little different from the standard method of producing bench grafted plants in the U.S. (callusing in the dark, hardening off callused plants in a greenhouse, then field planting). Systems similar to the one described here are used on a large scale in France, but the callusing step is done in a greenhouse instead of a small container.

If you are interested in trying your own grafting, start on a modest scale to get experience with how the system works and what sort of success you have. Most failures are the result of using poor wood, so make sure you can secure a good source of quality plant material and can store it properly until April.