Control for purple blotch and anthracnose diseases using biopesticides and local varieties of shallots in the rainy season

Purple blotch and anthracnose disease are the main diseases of shallots. The purpose of this study was to obtain an environmentally friendly technology for controlling purple blotch and anthracnose on shallots during the rainy season. The design used in this research was a split plot design with the main plots of local varieties of shallots (A) namely Sembrani, Bima Brebes and Maja Cipanas. As a sub-plot is the use of fungicides, namely chemical fungicides, chemical fungicides and bio-fungicides are used interchangeably and bio-fungicides are used routinely. The results of research conducted in the rainy season show that Sembrani variety had a significant effect on reducing the severity of purple blotch, anthracnose, and Stemphylium leaf blight disease compared with Bima Brebes and Maja Cipanas varieties. The use of chemical fungicides continuously is comparable to use of chemical fungicides and bio-fungicides which are carried out alternately in suppressing the severity of purple blotch, anthracnose and Stemphylium leaf blight diseases on shallots. Control by using chemical fungicides and bio-fungicides alternately that are can save the use of chemical fungicides by 50% thereby can protect the environment sustainability.


Introduction
Shallot is a vegetable commodity that has high economic value.The need for shallots increases every year, because many households in Indonesia consume it as a spice commodity.According to Indonesian central Statistics Bureau [1] in 2021 there will be an increase in shallot production by 10.4% from the previous year.With shallot production increasing every year, the shallot wide open for domestic market and export.Therefore, the quality of shallots that are good and safe for consumption is the main thing.
However, the average national production is still low [2] compared to the yield potential of shallots.The supply of shallots is very volatile and is not available all the time, especially before the rainy season, because cultivation is generally carried out during the dry season (on season) [3].In an effort to meet the needs of shallots, productivity needs to be increased and the provision of seeds outside the growing season needs to be pursued by providing seeds from disease tolerant local varieties which usually develop at the change of season from the dry season to the rainy season or from the rainy season to the dry season, where at that time there was a very different change of weather.
One obstacle to the production of shallot production off season, especially in the rainy season is the attack of purple blotch caused by Alternaria porri and the attack of anthracnose or automatic disease caused by the pathogenic fungus Colletotrichum gloeosporioides [4].Both attacks can cause up to 100% damage in a relatively short time, where the affected plants can't produce.The development of these two diseases in shallot plants, especially anthracnose, develops very rapidly in line with the anomaly of rainy climate throughout the year.
For this reason, it is necessary to control ways to control anthracnose and purple blotch, among others by using resistant or tolerant varieties of the disease.However, to date no local varieties have been found that are resistant or tolerant to anthracnose and or purple blotch diseases [5].
The Indonesian Vegetable Research Institute (IVEGRI) has released several varieties of shallots that are suspected to be resistant / tolerant to purple blotch and anthracnose diseases, but have not been evaluated for their resistance to both diseases, especially in the rainy season.Vegetable varieties can produce well which allows them to cope with extreme climates under high temperatures, drought stress, increased soil salinity, and pest attack [6].On the other hands IVEGRI has also obtained the main pest control technology of shallots and its application has been able to reduce the use of synthetic pesticides.However, with the very rapid development of pests, improvements to existing technologies and assembly of new technology components that are environmentally friendly are needed.Integrates Pest Management (IPM) is a disease control system that uses an integrated approach between ecology, biology, agroecosystems and chemistry, so it is necessary to understand each of these sciences [7].Through this understanding, it can be seen that the factors that influence the development of purple blotch and anthracnose can be manipulated as a control component.One other control component is the application of the use of chemical fungicides and bio-fungicides.The use of chemical fungicides and bio-fungicides will not damage the environment if used appropriately and correctly.For this reason, it is necessary to re-evaluate how to use it during the rainy season.The purpose of this study was to obtain an environmentally friendly technology for controlling purple blotch and anthracnose diseases on shallots base on varieties and fungicides during the rainy season The size of plot treatment 10 m x 7.5 m consisting of 5 beds with a population of 500 plants / treatment/ plots.The planting distance used is 20 x 20 cm and the distance between treatments is 100 cm.The treatment begins when the shallot plant has grown 100% or aged about 2 weeks after planting.Fertilization is done with N fertilizer 180 kg / ha, P2O5 80 kg / ha and KCl 140 kg / ha.Observations were made on the severity of purple blotch, anthracnose and Stemphylium leaf blight disease.The yield of shallot bulbs was weighed per treatment and per replication.Observational data were analyzed according to the design used.Differences between treatments were analyzed using BNJ at the 5% level.

Result and discussion
Disease attacks on shallot plantations were found starting at the age of 42 days after planting.Observations were made 3 times with an interval of 7 days.The results of observations on shallot plantations found that there were attacks of purple blotch disease, anthracnose and Stemphylium leaf blight with different disease severity.In general, the attack rate of purple blotch disease, anthracnose and Stemphylium leaf blight are relatively low, although planting is done in the rainy season.Spraying is done once every 7 days according to the treatment being tested.Anthracnose disease is an important disease in shallots, especially during the rainy season [8][9].

A Purple blotch disease severity (A. porri)
The effect of local varieties of shallot and use of fungicides on the severity of purple blotch disease in various observations can be seen in Table 1.The treatment of shallot varieties and use of fungicides on plants aged 42, 49 and 56 days after planting (DAP) against purple blotch disease did not occur interaction.The severity of purple blotch disease in the tested shallot varieties, namely Sembrani, Bima Brebes and Maja Cipanas, did not show a significant difference.At observations 49 and 56 DAP, the severity of purple blotch was lowest in the treatment with chemical fungicides and significantly different from the bio-fungicide treatments used routinely.However, it was not significantly different from the chemical fungicide and bio fungicide treatments which were used interchangeably.Control of purple blotch disease using chemical fungicides interspersed with the use of bio-fungicides can reduce the use of chemical fungicides by 50%.
Table 1.Effect of shallot varieties and fungicide against a purple blotch disease severity

Anthracnose disease severity (Colletotrichum sp.)
Result of observation of the disease severity of the anthracnose disease on the observation of 42, 49 and 56 DAP showed no interaction.The variety of Sembrani has a significant effect on the disease severity of anthracnose at 49 and 56 DAP, when compared with the variety of Maja Cipanas and not significantly different with the Bima Brebes variety.Maja Cipanas variety was tolerant to anthracnose based on the results of artificial inoculation in the screen house and natural inoculation in the field during the rainy season [10].In addition, isolate virulence factors [11] and optimal environment can influence the development of anthracnose disease in the field [12].
The variety of Sembrani has a significant effect on the severity of anthracnose disease at 49 and 56 DAP, when compared with the variety of Maja Cipanas and not significantly different from the Bima Brebes variety.The treatment of chemical fungicides was not significantly different from the treatment of chemical fungicides and bio-fungicides which were used alternately with the lowest disease severity of anthracnose.However, bio-fungicide treatments that are used routinely are significantly different.The incidence of anthracnose caused by the pathogenic fungus C. Gloeosporioides on shallots increased in line with the climate anomaly where high intensity rain fell during the off-season [13,14].Breeding by producing varieties resistant to anthracnose is one of the environmentally friendly controls.However, the availability and diversity of highly resistant genes for this disease is very limited, as well as the diversity of anthracnose isolates used in selection and testing.
Table 2. Effect of the shallot varieties and fungicides to disease severity of anthracnose

Disease severity of Stemphylium leaf blight disease (Stemphyllium sp.)
Results of statistical analysis on the observation of severity of stemphyllium leaf blight disease occured interaction between variety and fungicides at 49 HST observations.The Sembrani variety is not significantly different from Maja Cipanas variety and is significantly different from Bima Brebes variety.The variety of Sembrani shows a low disease severity of stemphyllium leaf blight disease.The use of chemical fungicides is better than the use of chemical fungicides which are used alternately with bio-fungicides and -that are used routinely.Stemphylium leaf blight disease has started to develop in the field, such as in West Sumatra [15] which causes plant aging and small tuber size [16].4. interaction between the use of shallot varieties and fungicides at 49 DAP

Yield
The yields of the Sembrani, Bima Brebes and Maja Cipanas varieties of shallot showed no significant differences from each other, ranging from 27.66 -24.20 kg/75 m2 (Figure 1.).Use of chemical fungicides and bio-fungicides singly or interchangeably resulted in yields that were not significantly different (Figure 2.).Yield in fungicide treatment ranged from 26.60 -24.86 kg/75 m2.

Conclusion
The results of research conducted in the rainy season show that the Sembrani variety had a significant effect on reducing the severity of purple blotch, anthracnose, and stemphylium disease compared with the Bima Brebes and Maja Cipanas varieties.The use of chemical fungicides continuously is comparable to the use of chemical fungicides and biofungicides which are carried out alternately in suppressing the severity of purple blotch, anthracnose and stemphyllium diseases on shallots.Control by using chemical fungicides and biofungicides that are carried out alternately can save the use of chemical fungicides by 50% thereby can protect the environment sustainability.
activities were carried out at the Agricultural Technology Research and Development Installation Margahayu Lembang (± 1,250 m asl) from September to December 2020 during the rainy season.In this research using a Split Plot design and repeated 3 times.The treatments tested are as follows: Main plot : A. Local varieties of shallot a1.Sembrani a2.Bima Brebes a3.Maja Cipanas Sub Plot : B. Fungicide b1.Control I (Chemical fungicide) (Azoxystrobin + difenoconazole) b2.Control II ( Chemical fungicide -alternated Bio-fungicide) b3.Control III (Biofungicide ) (Bionutri-V+Biosterilan)

Figure 1 .
Figure 1.Effect local varieties of shallot to yield

Figure 2 .
Figure 2. Effect Fungicide to yield

Table 3 .
Effect of shallots varieties and fungicides to Stemphylium leaf blight disease severity

Table 2 . Effect of the shallot varieties and fungicides to disease severity of anthracnose
* DAP: Day After Planting Table

Table 4 . Interaction between the use of shallot varieties and fungicides at 49 DAP
Mean followed by the same letters in each observation are not significantly different according to BNJ 5%. *