In January 2020, officials from Agricultural Office along with representatives of Apple Grower Association visited ICSFRI to report about the incidence of fruit rot attack on apple orchard in Batu. Based on MoU between ICSFRI and Batu City Government in 2019 for technology guidance in cultivation of apple, citrus and strawberry, ICSFRI required to take action to help the farmers manage the disease.
Field Visit and Observation
ICSFRI represented by researcher from Department of Pest and Disease Management visited several orchards in Batu in different altitude i.e. three orchards in Bulukerto (1000-1500 m asl), Sumbergondo (2000-2500 m asl), and Tulungrejo (2000-2500 m asl). These orchards have various farming system, with monoculture or polyculture with other plants. The team then took samples from these orchards and to further observed the cause of the disease.
In the laboratorium, it was identified from fungus culture that the cause of the disease was Gleosporium sp (Figure 1). The symptoms include irregular brown spots and black dots found on the surface of mature leaves which then spread to young leaves and finally cause them to fall. The symptoms could occur in 1-2 weeks and is really influenced by environment after leaf pruning, which left leaf dried and the infections spread to the twigs/branches).
The pathogen grow well in temperature of 30 ºC. The spread is promoted by wind and rain. Water can be absorbed by spores which causing further dispersal. Rainy season is the critical period of the disease attack when plants form new leaves. Gleosorium sp could infect plant directly without the need of wound to penetrate leaves and fruits through lenticels which usually needs one-week incubation period (Astuti et al., 1987 cit Nurawan & Sukamto 1992).
Recommendation of Disease control
Based on the observations, team from ICSFRI then presented a recommendation to control the disease on February 3, 2020 in front of 50 members of the apple farmer association and the Batu City Agricultural Office, as follows:
- It is necessary to conduct socialization and control measures by all stakeholders (Head of District, Village Head, Farmers Group, Batu City Apple Farmers Association, Apple Traders, and the community) who are in the apple planting area to raise awareness of this disease outbreak. For this reason, it is necessary to terminate the life cycle of fruit rot disease (Gloesporium sp.)
- Immediately take steps to suppress the outbreak of fruit rot by breaking the life cycle of apple rot disease (Gloesporium sp) through the following steps:
- Fruits attacked by the disease should not be dispose in any places such as yards, rivers, merchant warehouses, Temporary Waste Disposal Sites (TPS) in villages, and apple farmer gardens.
- Attacked fruits from orchard and public places should be collected and dispose in the final waste disposal site (TPA).
- Apple orchard manager/owner is recommended to carry out pruning of apple trees; the material pruned must be collected, buried in the ground or thrown into the landfill.
- Orchard sanitation should be conducted, such as cleaning bushes and weeds to reduce the suitable microclimate for the fungus Gloesporium sp.
- Application of systemic and contact fungicides is preferable at the start of the rainy season before any significant attack occurs.
- It is necessary to carry out demonstration plot activities for healthy apple orchards in farmers’ gardens, which are managed by farmers by applying the technology recommended by ICSFRI supervised by the Batu Agricultural Office Kota.
Batu Agricultural Office has responded to the recommendations by implementing direct control assistance on farmers’ land. In accordance with the concept of horticultural area assistance, mentoring is carried out by (1). Making demonstration plots in apple farmer fields; (2) Training on technologies for controlling apple fruit rot; (3) Institutional development, and (4) Assistance to farmers outside the demonstration plot.
Demonstration plots have been started in the three villages that have the most extensive apple plantations, namely Tulungrejo, Sumbergondo, and Bulukerto. The land for the demonstration plot was selected for plants that are more than 5 years old, already in the production phase and in a low condition for apple rot disease. The initial stage is to observe the extent and severity of the disease before the apples are harvested (Anang Triwirtano/tr:bq).