Boll weevil, Anthonomus grandis Boheman, resistance, which was expressed as reduced oviposition, was identified in several photoperiodic primitive stocks of cotton, Gossypium hirsutum L., in the early 1970's. The phot periodic stocks were crossed to 'Deltapine 161 and the progeny were selected for the day-neutral flowering habit. These progeny were then backcrossed twice to their respective original primitive stocks and selected for day neutrality after each backcross. The resulting BC(2)F₄ progenies of two of the primitive stocks (T-326 and T-1180) were evaluated using a laboratory technique to measure boll weevil oviposition.

Oviposition in the original primitive stocks, T-326 and T-1180, was expressed as 36 and 30% as much as on the control, M-8, for the two stocks, respectively. The BC(2)F₄ progeny of T-326 and T-1180 expressed resistance as 57 and 54% as much oviposition as on 'Stoneville 213' In a laboratory test and resistance also was noted In a field test. The mechanisms of resistance are unknown; however, we are in the process of determining if the resistance has a chemical basis.

Results of agronomic evaluation of the progeny of the two stocks showed that they had lower lint percent, smaller bolls and about one-half the yield of Stoneville 213, but the fiber properties were similar to those of Stoneville 213. Even though the primitive stocks are deficient in factors affecting agronomic performance they will flower and thus, are readily usable as boll weevil resistant parents.