This study -was carried out to compare the efficiency of some recently introduced, systemic and contact fungicides in the control of seedling damping-off and Stemphylium leaf spot of broad bean. The present work showed that damping-off of broad bean is mostly caused by a complex of some soil fungi, the disease was successfully controlled by seed dressing with Benlate thiram (4 g/kg seeds) and Brassicol (PCNB) at the same rate. Thus, higher seedling stands were produced by these treatments. Both fungicides as well as those known to have a systemic action were also recorded to reduce Stemphylium
leaf spot incidence. Effect of different fungicides on plant growth, nodulation and yield was also investigated. Benlate T, Vitavax captan and Brassicol treated seeds gave longer roots and better nodulation. However, the two former fungicides only gave a significant increase in the seeds yield per plant. It was also shown that the combination of carboxin (i.e. Vitavax) and captan (i.e. Orthocide 83), in one compound namely; Vitavax captan was of super effect in damping-off control than each one separately.
Broad bean (Vicia faba L.) is the major annual leguminous crop in
Egypt (A.R.E.). This crop is subjected to the attack of many diseases at various stages of plant growth which affect the root and the shoot systems (1, 2, 3, 4, 12, 18, 21). One of the serious diseases, is the seedling damping-off at pre- and post-emergence stages of seedling development. This disease almost caused a reduction in seedling stand which indirectly affects the total yield per cultivated area. Shoot system is frequently affected by the invasion of many pathogenic fungi, from which Stemphylium leaf spot was reported to cause severe necrosis to leaflets and subsequently causes premature defoliation (10).
Seed dressing treatments were employed for damping-off control by many investigators, whenever new fungicides were introduced to the country (13, 14, 23). Also, Stemphylium leaf spot was successfully controlled by foliar spray with some contact and systemic fungicides (15).
In a recent work carried out by the authors (11), it was found that some fungicides, particularly those of systemic action, could be used for the double purpose of damping-off control of cucurbit seedlings and thereafter on the powdery mildew at the latter stages of plant growth.
This work was therefore designed to test some of the recently introduced fungicides, either of contact or systemic action, on damping-off control and also their residual effect in mature plants as indicated by the incidence of Stemphylium leaf spot on broad bean plants. |
