IN VITRO SELECTION AND COMMERCIAL RELEASE OF GUAVA WILT RESISTANT ROOTSTOCKS

Guava Wilt Disease (GWD) has resulted in the loss of more than half the guava plantings in the North Eastern region of South Africa.
Control measures, other than eradication of diseased trees, do not exist.
Consequently, it was of critical importance for the guava industry that a cultivar with an adequate degree of tolerance was found, and that the trees could be rapidly multiplied for commercial release before the industry collapsed.

Cell free filtrates derived from Penicillium vermoesenii were used to screen thirty thousand guava seedlings in vitro. Ten promising selections were made and cloned in tissue culture.
Three of the selections exhibited 100% tolerance or resistance to GWD.

The major advantage of using this technique to screen for resistance, is that the juvenile growth phase of the plants could be maintained.
This facilitated the use of nodal and split-nodal cuttings from tissue culture derived rammets instead of the slow, conventional propagation techniques such as air-layering and hardwood cuttings.
As a result, 25 % of the trees lost to GWD in South Africa have been replaced by trees with tolerant rootstocks within a research period of five years.

XXV International Horticultural Congress, Part 3: Culture Techniques with Special Emphasis on Environmental Implications, Disease, Pest Control and Integrated Pest Strategies

J.E. Vos, M.H. Schoeman, P. Berjak, M.P. Watt, A.J. Toerien

in vitro screening, in vitro culture, Penicillium vermoesenii, Psidium guajava, guava, phytotoxin, plant pathogenic fungi, propagation, root stocks, tissue culture, disease resistance

https://doi.org/10.17660/ActaHortic.1998.513.7