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2CONTROL MEASURES FOR DOWNY MILDEW DISEASE OF
BRASSICACEAE VEGETABLE CROPS
A.N. Allayarov1
The effect of certain fungicides approved for use against this disease of Brassicaceae vegetable crops has been studied, it has also been found that the cultivation of cabbage seedlings and crops led to the formation of a natural infectious background of fungi that cause downy mildew disease. In the greenhouses where downy mildew disease was recorded, the fungicides Shavit F 72% w.s.g. at rates 0,15 g, 0,20 g and 0,25 g per 1 m2 area, Kurzat R w.p. at rates 0,25 g, 0,30 g and 0,35 g per 1 m2 area were applied against the disease. Bordo fluid of 1% was used as a standard option. Conducting experiments in such environment was a necessary factor to correctly evaluate the effect of fungicides on the disease.
Key words: Disease, cabbage, downy mildew, Shavit F, Kurzat R, Bordo fluid, standard, fungicides.
Introduction. Brassicaceae vegetables (white cabbage, cauliflower, broccoli, savoy, Chinese cabbage, bok choy cabbage and others) have a special place among vegetable crops, in January 2022, the export volume of the main types of cabbage in Uzbekistan increased significantly. The reason for this is the sharp increase in demand for this product in foreign markets. In February, the situation in the main foreign markets was also favorable for farmers and experts in the production of white cabbage, Chinese cabbage, cauliflower and broccoli (East Fruit 2022). Brassicaceae crops occupy the third place after tomatoes and onions in the total area of vegetable crops grown in our republic (Ostonakulov, Zuev, Kodirkhojaev 2009). According to the preliminary data of the Customs Committee of the Republic of Uzbekistan, in February 2022, the volume of exports of the main types of cabbage crops was as follows:
White head - 17,2 thousand tons, cauliflower and broccoli - 2,5 thousand tons, Chinese cabbage - 710 tons, and it can be seen that this indicator is 3,6 times more than in February 2021 (East Fruit 2022).2 The area of origin of Brassicaceae is considered to be the shores of the Mediterranean Sea, and it belongs to the group of very ancient crops (Shokirov, Azimov, Lapasov 2017). Although the composition of cabbage is not rich in nutrients, it is a source of minerals, vitamins and especially vitamin C (Ostonakulov, Zuev, Kodirkhojaev 2009).
Brassicaceae vegetable crops are affected by a number of viral diseases (Cauliflower mosaic virus, Turnip mosaic virus), bacterial diseases (Pseudomonas syringae. pv. maculicola, Erwinia spp, Xanthomonas campestris pv. campestris) and fungal diseases (Phoma lingam, Fusarium oxysporum f. sp. conglutinans, Verticillium dahliae, Sclerotinia sclerotiorum, Mycosphaerella brassicicola, Peronospora parasitica, Plasmodiophora brassicae, Pythium spp., Fusarium spp., Rhizoctonia solani) at their growth, development and shelf life periods (Khasanov, Ochilov, Gulmurodov, 2009; Allayarov, Abdurakhmanova, Khakimov, 2019).
The overuse of synthetic pesticides without control and without thinking about their effects leads to soil pollution with pesticides, the emergence of extremely high resistance to them in harmful organisms, a sharp increase in the amount of pesticide residues in food products, the death of organisms useful to mankind, and most importantly, it causes great damage to human health. In order to avoid such situations, it is necessary to use synthetic pesticides only when the harmful organism exceeds the economic threshold, or to replace synthetic pesticides with substances of biological
1 Allayarov Abdurakhman Nazaralievich - Department Agrobiotechnology, Tashkent State Agrarian University, Uzbekistan.
2EastFruit 2022 https://east-fruit.com/author/east-fruit/
origin based on microorganisms, or biopreparations obtained on the base of microbial producers and colony-forming units (Khakimov, Omonlikov, Utaganov, 2020).
A number of scientists reported the emergence of resistance of pathogens to synthetic fungicides (Korolev, Mamiev, and Elad, 2010; Mamiev et al., 2013; Zuparov et al., 2020; Mamiev et al., 2020), in its turn, it encourages the use of biofungicides against disease-causing fungi.
Materials and Methods. When studying the downy mildew disease of Brassicaceae vegetable crops, 100 seedlings were examined from each nursery greenhouse, for this case 10 samples with 10 seedlings in each were taken. Healthy and diseased seedlings of each sample were separated. The count of the number of infected leaves of diseased seedlings was taken. It was observed that inconspicuous yellow spots appeared on the surface of the leaves of seedlings of Brassicaceae vegetable crops infected with downy mildew disease. MIKMED-5, Binocular BMS-2 microscopes were used to identify downy mildew pathogens. Their species was identified (Khokhryakov M.K. 1968). Determinants by N.M. Pidoplichko, V.I. Bilay and other determinats were used to identify the types of fungi. Statistical analysis of research results was carried out by the method of B.A. Dospekhov.
Downy mildew disease of Brassicaceae vegetable crops is found in Sweden, Denmark, Scotland, Germany, France, Austria, Hungary, Italy, Yugoslavia, Romania, India, Japan, USA, Argentina, Azerbaijan, Armenia and a number of other countries. Cabbage is more affected by this disease in greenhouse conditions(Tunkina, 1955; Kuziev, 1989; Nighat et al., 2013).
Information about this disease in Uzbekistan can be found in the works of N. G. Zaprametov (1955). Scientists V.A. Tagirova (1967) and E.A. Kuziev (1989) studied downy mildew disease in the condition of Tashkent region.
Results and Discussion. We propose that it is expedient to disinfect the seeds against the downy mildew disease in the seedlings of Brassicaceae vegetable crops, to design the density of the seedlings properly, and to choose the disease-resistant varieties correctly.
Against the downy mildew disease in the seedlings of Brassicaceae vegetable crops, the fungicides approved for use against the downy mildew disease of agricultural crops in our republic, but not tested on Brassicaceae vegetable crops, such as of Shavit F 72% w.s.g. and Kurzat R w.p. preparations at different concentrations were applied in the greenhouses where the disease was recorded.
In the greenhouses where downy mildew disease was recorded, the fungicides Shavit F 72% w.s.g. at rates 0,15 g, 0,20 g and 0,25 g on 1 m2 area, Kurzat R w.p. at rates 0,25 g, 0,30 g and 0,35 g on 1 m2 area were applied against disease. Bordo fluid of 1% was used as a standard option.
Seedlings from the fungicide-free field were used for control option.
Before spraying fungicides and after 5 and 10 days from spraying, diseased and healthy seedlings were counted and recorded. From each plot, 5 samples by 50 plants were collected for checking. Diseased and healthy plants and infected leaves of diseased plants were counted in each sample and recorded regularly.
Table-1
The effect of fungicides on downy mildew of the seedlings _of Brassicaceae vegetable crops__
№ Experiment options Application rate of fungicide, g/m2 Disease prevalence, % Disease development, % Biological efficiency of preparations, %
1 2 3 4 5 6
White cabba ?e
1 ShavitF 72% w.s.g. 0,15 16,1 7,5 76,7
0,20 13,4 5,7 82,4
0,25 10,2 3,3 89,7
2 Kurzat Rw.p. (B) (42+397,5) 0,25 17,3 8,9 72,4
0,30 15,5 7,1 78,0
0,35 14,8 6,2 80,8
3 Bordo fluid (standard) 0.6 (by copper cup) 16,7 7,9 75,5
4 Control - 49,5 32,3 -
End of the Table-1
Cauliflower
1 ShavitF 0,15 16,2 7,3 75,0
72% w.s.g. 0,20 11,8 4,9 83,2
0,25 9,4 3,0 89,7
2 Kurzat 0,25 15,9 7,2 75,3
Rw.p. (B) 0,30 12,7 6,1 79,1
(42+397,5) 0,35 13,4 5,0 82,9
3 Bordo fluid 0.6 15,3 77,4
(standard) (by copper cup) 6,6
4 Control - 46,1 29,2 -
Red cabbage
1 ShavitF 0,15 3,1 1,7 82,1
72% w.s.g. 0,20 2,0 1,2 87,4
0,25 1,1 0,8 91,6
2 Kurzat 0,25 6,7 2,1 77,8
Rw.p. (B) 0,30 3,0 1,8 81,0
(42+397,5) 0,35 2,2 1,3 86,3
3 Bordo fluid 0.6
(standard) (by copper cup) 5,6 1,9 80,0
4 Control - 18,2 9,5 -
Chinese cabbage
1 ShavitF 0,15 7,1 3,0 80,8
72% w.s.g. 0,20 3,9 2,1 86,5
0,25 3,6 1,3 91,7
2 Kurzat 0,25 8,5 4,0 74,3
Rw.p. (B) 0,30 7,4 3,2 79,5
(42+397,5) 0,35 6,0 2,2 85,9
3 Bordo fluid 0.6
(standard) (by copper cup) 7,4 3,2 79,5
4 Control - 21,3 15,6 -
Broccoli
1 ShavitF 0,15 8,8 3,5 79,5
72% w.s.g. 0,20 7,9 2,7 84,2
0,25 4,6 1,7 90,1
2 Kurzat 0,25 12,4 4,7 72,5
Rw.p. (B) 0,30 9,4 3,4 80,1
(42+397,5) 0,35 8,1 2,8 83,6
3 Bordo fluid 0.6
(standard) (by copper cup) 9,2 3,7 78,4
4 Control - 25,6 17,1 -
It is evident from table-1 that the highest biological efficiency was recorded in the option treated with Shavit F 72% w.s.g. at the rate of 0,25 g perl m2 area against downy mildew disease of Brassicaceae vegetable crops. Biological efficiency in this option was 89,7% in white cabbage, 89,7% in cauliflower, 91,6% in red cabbage, 91,7% in Chinese cabbage, 90,1% in broccoli. In a standard option with Bordo fluid this indicator was 75,5%, 77,4%, 80,0%, 79,5% and 78,4% respectively.
Therefore, it is expedient to recommend the application of Shavit F 72% w.s.g. fungicide at the rate of 0,25 g per 1 m2 against the downy mildew of Brassicaceae vegetable crops.
Conclusion
Therefore, it is expedient to recommend the application of Shavit F 72% w.s.g. fungicide at the rate of 0,25 g per 1 m2 against the downy mildew of Brassicaceae vegetable crops.
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© A.N. Allayarov, 2022.
