The Efficiency of Some Safe Alternative Methods in Controlling Alternaria Leaf Spot on Broad Beans Caused by the Fungus Alternaria sp.

Abstract

Abstract The study aimed to isolate and diagnose the cause of alternarial leave spote in broad beans and to evaluate the efficiency of some extracts and fertilization treatments in applying them in the field and their effect in reducing the effect of the disease and reducing the loss in the growth and production traits of the broad bean. The pathogenic fungus was isolated from bean plants that showed infection symptoms and was identified molecularly using PCR technology. The effectiveness of some plant extracts (rosemary, licorice, ginger) and some substances (organic copper, potassium silicate, zinc) in three concentrations inhibiting the fungus Alternaria alternata was evaluated in vitro. Laboratory results showed that organic copper treatment inhibited the fungal colony, and the inhibition rate reached 100% at all concentrations. This was followed by treatment with potassium silicate when the inhibition rate reached 52.08%. As for plant extracts, ginger extract achieved the highest rate of fungal inhibition at a concentration of 10% 79.83%, with a colony diameter of 1.5 cm. Measurements were taken after the growth of the control had been completed, after 5-7 days. The results indicate that all the treatments used significantly reduced the infection rate compared to the control treatment; however, there was a significant difference in the rate of effect of these treatments. The organic copper treatment achieved the lowest infection rate, followed by the seaweed extract treatment, with a percentage of infection rates of 34.44 and 35.00, respectively. The least effective was the ginger extract treatment, although it was significantly different from the control treatment, with the infection rates reaching 83.47 and 68.33, respectively. The results indicate that all the treatments used achieved a significant difference in reducing the severity of infestation compared to the control treatment despite a significant difference in the average effect of these treatments. The organic copper treatment achieved the lowest infestation severity, followed in second place by the seaweed extract treatment, which reached the lowest severity. The infection severity was 0.24 and 0.27, respectively. The least effective treatment was the ginger extract treatment, although it was significantly different from the control treatment, where the infection severity reached 0.56 and 0.72, respectively. Results showed that the average effect of the treatment on organic copper gave the highest level of chlorophyll, while ginger extract gave the lowest level of chlorophyll, which reached 53.45 and 25.40 SPAD, while the sound control treatment without any addition gave the highest level of chlorophyll, reaching 67.09 SPAD. The results show that all the treatments used achieved a significant difference in leaf area compared to the polluted control treatment despite a significant difference in the effect rate of these treatments. The organic copper treatment achieved the highest leaf area, followed in second place by the seaweed extract treatment, reaching 13.24 cm2. 11.83 cm2, respectively, and the least effective treatment was ginger extract, although it significantly differed from the control treatment when they reached 7.33 cm2 and 4.98 cm2. The results show that the average effect of the treatment for organic copper gave the highest level of increase, followed in second place by seaweed extract, followed in third place by potassium silicate, while Ginger extract gave the lowest level of plant height, which reached 57.14, 52.96, and 48.25 cm. The results indicate a significantly excelled soaking + spraying method over the soaking-only method in all traits mentioned.