الفهرس 
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Abstract
Virus diseases - at present - are limiting to tomato production. The major two viruses are tomato yellow• leaf curl and the TMV. To furnish –knowledge about these two diseases, •the present work was carried out in the yea.rs 1973-1976. It comprised four angles• namely, the effect of these two viruses on growth and yield the search of resistance to these pests including the inheritance of this character. It also comprise the effect of some nutritional foliar sprays as a trial to reduce the deleterious effects of these viruses. For this six trials were made at the greenhouse and five in the
.field. The results were as follows: I. Tomato yellow leaf curl virus (TYLCV): l- Fifteen virulefrous white flies (Bemisia tabaci) can successfully transmit TYLCV to tomato seedlings. 2. Under greenhouse conditions the incubation period necessary for the appearance of virus symptoms was 2-4 weeks after inoculation. 3. Symptoms were slight cholorosis, Lamila curling between the veins slight upward rolling of the margins in addition to reduced size of young leaves. The infected plants were stunted and unproductive. 4. Both Ace and L pimpinellifolium LA 121 a.re susceptible to TYLCV under greenhouse conditions during the early summer season. 5. Out of 35 cultivars tested in October under insect proof cages in the greenhouse, Avalanche mm nova and L. peruvianum were free of infection.