Document Type : Research Article
Authors
1
Plant Disease Research Department, Iranian Research Institute of Plant Protection, AREEO, Tehran, Iran
2
Plant Protection Research Department, Agricultural and Natural Resources Research Center of Khuzestan Province, AREEO, Ahvaz, Iran
3
Plant Protection Research Department, Agricultural and Natural Resources Research Center of Tehran, AREEO, Varamin, Iran
Abstract
Introduction
The cultivation of vegetable crops under greenhouse condition is an important strategy to increase productivity and total production in Iran. Environmental conditions (high humidity and proper temperature) are favorable for the emergence and spread of diseases. Sometimes, despite of good agricultural operations, the incidence of downy and powdery mildew may have resulted a severe economic loss. So, the application of fungicides to control fungal diseases is inevitable. Several airborne diseases have affected the cultivation of greenhouse cucumbers. Powdery mildew disease, caused by Golovinomyces cichoracearum is one of the most important diseases of cucumber (Cucumis sativus). Due to the importance of producing a healthy crop, extensive research has been conducted to reduce the use of chemical pesticides and find alternatives to these substances in various plants. Given the fresh consumption of cucumbers and the importance of pesticide residues, and in order to produce a healthier crop, the need to use effective, low-cost and low-risk fungicides is doubly urgent. Microbial and plant-based fungicides are promising alternate for chemical fungicides. This study was conducted to investigate the efficacy of the plant-based fungicides Mildew cut and Allicin in controlling powdery mildew disease in cucumber. Mildew Cut fungicide contains 10% garlic oil (0.03% allicin) and 3% clove essential oil (2.2% ozonol) and has an EC formulation of 13%. This is a protective fungicide and the presence of oil in its formulation causes the formation of a protective layer on the surface of the host leaf and prevents the attachment, germination of fungal spores and the entry of the spore tube and mycelium causing superficial powdery mildew into the host. Allicin fungicide is a biological fungicide based on plant extract and with the trade name Allicin and with a microcapsule formulation (ME 5%).
Materials and Methods
In this research, the efficacy of two plant base fungicides including Mildew cut (EC 13%) at the rate of 4, 5, 6 g.L-1 and Allicin (ME 5%) at the rate of 0.5, 1 and 1.5 g.L-1 was evaluated to control cucumber powdery mildew disease in greenhouse conditions. Their effectiveness was compared with Cidely Top and a water-treated control. This research was conducted in the form of randomized complete block design with eight treatments and three replications, conducted across two provinces, Tehran and Khuzestan. Each experimental plot was four meters long and consisted of two rows of plants with a row spacing of 25 to 30 cm and a plant spacing of 30 to 35 cm in each row. In each experimental plot, 10 plants were randomly selected and marked. When the first signs of disease were observed, the desired treatments were applied using a 20-liter backpack sprayer. The sprays were repeated at 7 to 10 day intervals until disease severity in the control plots exceeded 50%. The evaluation of disease severity was performed before each spraying by Horsfall and Barratt method using a scoring system of one to seven (Horsfall and Barrat,. 1945)
Results and discussion
The obtained data fromboth regions showed that allicin, at concentrations of 1 and 1.5 g.L-1 exhibited 83 and 88.08% control efficiency, respectively. Similarly, Mildew cut, at concentrations of 5 and 6 g.L-1 provided control efficiencies of 84.6% and 86.6%, that were comparable to the Cidely Top as the control treatment (0.75 g.L-1) with 82.7% efficiency. The results of the current research indicated that the plant-based fungicides, Mildew cut at a concentration of 5 g.L-1 and Allicin at a concentration of 1g.L-1 can be suggested as a substitute or alternately with chemical fungicides to control powdery mildew disease of cucumber. Following appearance of disease symptoms, foliar spraying begins and repeat for two to three times at an interval of 7 to 10 days. The use of fungicides as a complement to the management strategies of airborne diseases such as powdery mildew, is necessary. Moreover, the emergence of resistance to fungicides and the need to replace high-risk fungicides with safe and plant-based products, continuous evaluation of new fungicides is crucial. The results of the present study showed that the plant-based compounds including Mildew cut (5 g.L-1) and Allicin (1 g.L-1) can be used as substitutes or in alternation with chemical fungicides in integrated management of cucumber powdery mildew.
Conclusion
Our findings indicated that the plant-based fungicides Allicin (1 g.L-1) and Mildew Cut (5 g.L-1) exhibit control potency comparable to that of the chemical fungicide Cidely Top. These products can may be used utilized as complementary options in integrated management strategies against cucumber powdery mildew.
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