Russian wheat aphid, Diuraphis noxia (Kurdjumov), is an important pest of wheat and barley in North America, Africa and the Middle East. Host plant resistance is the most economical and practical means of controlling this insect. Field and greenhouse screening in Syria of bread wheat lines from the International Center for Agricultural Research in the Dry AreasÕ (ICARDA) gene bank, using the Focused Identification of Germplasm Strategy (FIGS), identified 12 lines resistant to D. noxia. These sources of resistance will be used to develop germplasm resistant to D. noxia for the highland areas of North Africa, and West and Central Asia, where this insect causes economic damage. This study also showed the relevance of the FIGS approach in better targeting accessions held in gene banks for valuable traits.

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Cotyledons of 3 cultivars of pickling cucumber (Cucumis sativus L.) were partially or wholly removed during early seedling development to determine the effect of reduced seedling vigor on subsequent sex expression. Under winter conditions in the greenhouse, removal of 11/2 to 2 cotyledons led to reduced seedling vigor, an increase in the number of staminate flowers, and a reduction in the number of pistillate flowers on the first 10 nodes of the hybrid cultivars ‘Pioneer’ and ‘Pickmore’. During spring trials, removal of the cotyledons led to a vigor reduction in young seedlings, but mature plants were not stunted. Under conditions which were more favorable for plant growth, sex expression was unaltered in the plants. Sex expression was generally unaffected by cotyledon removal in an inbred line ‘MSU 713-5’ in both winter and spring trials, although the number of pistillate flowers produced was reduced by removal of both cotyledons 3 or 6 days after emergence in the spring trials. It appears that major loss of cotyledonary tissue can lead to an alteration of sex expression in hybrid cucumbers grown under less than optimum conditions for plant growth.

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