Extension Officer, Hadera Branch, Ministry of Agriculture.
Deceased 9 Nov. 1986.
Received for publication 7 July 1986. This work was partially supported by the Israeli Ministry of Agriculture. The skilled technical help of J. Costo and D. Galili is gratefully acknowledged. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.