Occurrence and distribution of fruit rot disease of chilli in Chitradurga Davanagere and Haveri districts of Karnataka

Introduction

Chilli (Capsicum annuum L.) is an important spice and vegetable crop cultivated extensively in India and is valued for its pungency, colour and wide range of culinary and industrial uses. The crop is affected by several diseases, among which fruit rot or anthracnose is one of the important diseases affecting fruit quality and marketable yield. Fruit rot of chilli is predominantly associated with species of Colletotrichum, and disease development may vary considerably with location, environmental conditions, crop stage and pathogen variability. The distribution and severity of chilli anthracnose can vary substantially among production regions. A survey conducted in major chilli growing areas of Andhra Pradesh and Tamil Nadu reported disease severity ranging from 8.13 to 38.66 per cent, demonstrating considerable variation among locations (Chowdary et al., 2024) [1] . Recent investigations in Karnataka have likewise demonstrated substantial variation in chilli anthracnose severity among districts. Variation in the per cent disease index of green and red fruit rot has been reported across major chilli-growing districts of northern Karnataka, with considerable differences among taluks (Vandana et al., 2025) [2] . Disease assessment through standardized rating scales and calculation of per cent disease index provides a useful means of comparing disease severity among locations. The 0-9 disease rating scale of Mayee and Datar (1986) [3] is widely used for field assessment of plant diseases, while per cent disease index can be calculated from numerical disease ratings following Wheeler (1969) [4] . Despite previous surveys in Karnataka, information on the occurrence and severity of chilli fruit rot in important chilli-growing areas of Chitradurga, Davanagere and Haveri districts during the 2025-26 cropping season was limited. These districts represent important chilli-producing areas with differences in agro-ecological conditions and soil characteristics. Therefore, a systematic survey was undertaken to assess the occurrence and severity of fruit rot of chilli in these districts and to determine variation in disease severity in relation to location, soil type and crop growth stage. The survey also provided rhizosphere soil samples for subsequent studies on associated bioinoculants.

Material and Methods

Survey Area and Period

The investigation was conducted during 2025-26 at the Department of Plant Pathology, College of Agriculture, Keladi Shivappa Nayaka University of Agricultural and Horticultural Sciences, Shivamogga, Karnataka. A roving survey was conducted in major chilli-growing areas of Chitradurga, Davanagere and Haveri districts of Karnataka. In each district, representative chilli-growing taluks and fields were selected for recording the occurrence and severity of fruit rot. The survey covered different villages representing variation in crop growth stage and soil type.

Survey and Sample Collection

An intensive roving survey was conducted in major chilligrowing taluks of the three districts. Representative fields were inspected for characteristic symptoms of fruit rot. Diseased plant samples were collected in sterile polythene bags, while rhizosphere soil samples from healthy chilli plants growing in the same fields were collected separately for subsequent isolation of rhizosphere-associated bioinoculants. The samples were transported to the laboratory under aseptic conditions and processed immediately. Information on district, taluk, village, crop growth stage, disease incidence, GPS coordinates and occurrence of other diseases was recorded using a standard survey proforma.

Assessment of disease incidence and severity

Disease incidence and severity were recorded from the surveyed fields. Per cent disease incidence (DI) and per cent disease index (PDI) were calculated using the standard procedure and formula given by Wheeler (1969) [4] .

Disease severity was assessed using the 0-9 disease rating scale of Mayee and Datar (1986) [3] described below.

Description of Disease Rating Scale (0-9)

Grade Description 0

No symptoms 1 1-10% or less infection 3 11-25% infection 5 26-50% infection 7 51-75% infection 9

Assessment According to Soil Type

The surveyed fields were categorized according to soil type. Disease incidence and PDI were calculated separately for fields under red and black soil conditions.

Assessment According to Crop Growth Stage

The surveyed fields were categorized according to crop growth stage at the time of observation. Fields at the fruiting and ripening stages were considered separately, and mean disease incidence and PDI were calculated for each stage.

Results

An intensive roving survey was conducted during 2025-26 to assess the occurrence and severity of fruit rot disease of chilli in major chilli-growing areas of Chitradurga, Davanagere and Haveri districts of Karnataka. The data on per cent disease incidence, per cent disease index, crop growth stage, soil type and other diseases observed, along with the GPS coordinates of the surveyed villages, were recorded using a standard survey proforma.

District-Wise Occurrence and Severity of Fruit Rot

Fruit rot was observed in the surveyed chilli-growing areas of all three districts. Disease severity varied among districts.

Haveri recorded the highest mean disease incidence (50.25%) and PDI (30.61%), followed by Chitradurga with 41.36 per cent disease incidence and 24.91 per cent PDI. Davanagere recorded the lowest mean disease incidence (38.25%) and PDI (22.17%) among the three districts (Table 2).

Taluk-Wise Severity

Disease severity varied considerably among the surveyed taluks. In Chitradurga district, Molakalmuru recorded the highest mean PDI (29.83%), followed by Hiriyur (24.44%) and Challakere (20.44%). In Davanagere district, Honnali recorded a mean PDI of 22.67 per cent, compared with 21.67 per cent in Channagiri. Among the surveyed taluks of Haveri district, Ranebennur recorded the highest mean PDI (35.78%), followed by Haveri (33.00%), Byadagi (32.00%) and Hirekerur (21.67%) (Table 3).

Effect of Soil Type on Disease Severity

Disease severity varied between the two soil types represented in the survey. Fields under black soil recorded higher mean disease incidence (48.71%) and PDI (29.62%) than fields under red soil, which recorded mean disease incidence of 42.10 per cent and PDI of 25.25 per cent (Table 4).

Effect of Crop Growth Stage on Disease Severity

Fruit rot severity was higher in crops at the ripening stage than in crops at the fruiting stage. The ripening-stage fields recorded a mean disease incidence of 46.88 per cent and PDI of 28.52 per cent, whereas fruiting-stage fields recorded 38.73 per cent disease incidence and 22.97 per cent PDI (Table 5).

Discussion

The present survey confirmed the occurrence of fruit rot of chilli in the major chilli-growing areas surveyed in Chitradurga, Davanagere and Haveri districts of Karnataka. Considerable variation in disease severity was observed among districts and taluks, indicating heterogeneous disease pressure across locations. Among the three districts, Haveri recorded the highest mean PDI of 30.61 per cent, followed by Chitradurga and Davanagere. The comparatively higher disease severity in Haveri is consistent with earlier surveys in Karnataka, which have documented substantial fruit-rot severity in Haveri and other northern Karnataka chilli-growing areas (Vandana et al., 2025) [2] . The variation observed among taluks in the present investigation may be associated with differences in local growing conditions and diseasefavouring environments. Ranebennur recorded the highest mean PDI among the surveyed taluks, while Hirekerur recorded the lowest PDI within Haveri district. Such location-specific variation has also been reported in earlier chilli anthracnose surveys (Chowdary et al., 2024; Raja et al., 2023) [1,5] . Disease severity was higher in black-soil fields than in redsoil fields. Black soil recorded a mean PDI of 29.62 per cent compared with 25.25 per cent in red soil. The present survey data indicate an association between soil category and disease severity; however, because soil type was observational rather than experimentally manipulated, this relationship should be interpreted as an association rather than a causal soil effect. Soil moisture and other environmental factors can influence infection and disease development, and differences in field moisture conditions may partly contribute to variation among soil types. A higher disease severity was recorded at the ripening stage than at the fruiting stage. The PDI increased from 22.97 per cent at the fruiting stage to 28.52 per cent at the ripening stage. Differential susceptibility of chilli fruits to Colletotrichum infection at different stages of maturity, including greater vulnerability of mature fruit to certain Colletotrichum species, has been reported in earlier studies (Saxena et al., 2014) [6] , and surveys of chilli anthracnose have frequently recorded disease during fruit development and maturation (Raja et al., 2023) [5] . The present observation therefore indicates that the ripening stage may represent an important period for monitoring fruit rot under field conditions. The overall findings demonstrate that fruit rot severity was not uniform across the surveyed region. Identification of locations with comparatively higher disease pressure, particularly in Haveri district and Ranebennur taluk, provides useful baseline information for targeted pathogen collection and development of biological diseasemanagement strategies. The rhizosphere soil samples collected during the survey also provided material for the subsequent isolation and screening of native bioinoculants in the present investigation.

Conclusion

The survey conducted during 2025-26 established the occurrence of fruit rot of chilli in the major chilli-growing areas of Chitradurga, Davanagere and Haveri districts of Karnataka. Disease severity varied considerably among districts, taluks, soil types and crop growth stages. Haveri recorded the highest mean disease incidence (50.25%) and PDI (30.61%), while Ranebennur recorded the highest mean PDI among the surveyed taluks (35.78%). Disease severity was comparatively higher in black soil (29.62% PDI) than in red soil (25.25% PDI) and at the ripening stage (28.52% PDI) than at the fruiting stage (22.97% PDI). The survey identified areas with comparatively higher disease pressure and provided baseline information for subsequent pathogen characterization and development of biological management strategies against chilli fruit rot.

Acknowledgments

The work was undertaken as part of the M.Sc. research programme at Keladi Shivappa Nayaka University of Agricultural and Horticultural Sciences, College of Agriculture, Shivamogga, Karnataka. The author is thankful to the advisory committee for their valuable guidance, support and encouragement throughout the research programme. The author also acknowledges the cooperation of the chilli-growing farmers who assisted during the survey and sample collection. The author sincerely expresses gratitude to the seniors and friends for their constant support, encouragement, cooperation and assistance throughout the course of the research work. The authors declare that there is no conflict of interest.

References

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