Response of Chili Pepper Genotypes to Pepper Yellow Leaf Curl Disease and Implementation of Disease Management by Farmers

Abstract

Chili pepper (Capsicum spp. L.) is a strategic horticultural commodity in Indonesia. Pepper yellow leaf curl disease (PYLCD) has caused significant losses for chili farmers in Indonesia, including in the central production area in central of Java. This disease is caused by Begomovirus infection and is transmitted by the whitefly, Bemisia tabaci, in a persistent and circulative manner. This research was conducted for two main objectives, (1) to characterize the performance of several chili genotypes and the development of PYLCD in the field and (2) to investigate and analyse farmers’ practices that may contribute to the PYLCD epidemic in central of Java. In the field experiment, six chili genotypes were planted in Ngablak, Magelang, Central Java, using a randomized complete block design with three replications. Meanwhile, the farmers’ survey involved 24 respondents from Brebes, Magelang, Temanggung, and Kulon Progo. Interviews were conducted using quantitative and descriptive questionnaires to determine knowledge, attitude, and practice (KAP) regarding PYLCD and the implementation of integrated disease management (IDM). Disease observation, detection, and virus identification were carried out on the field experiment crops and farmers' crops in Temanggung. This study confirmed the epidemic status of PYLCD in central of Java, characterized by high disease incidence in both field experiment and farmers’ survey locations. Virus detection using the polymerase chain reaction method successfully identified the predominant Begomovirus species, i.e., Pepper yellow leaf curl Indonesia virus, Pepper yellow leaf curl virus, and Tomato yellow leaf curl Kanchanaburi virus. The commercial variety ‘Asmoro 43-pnc’ was classified as resistant, and ‘Sios Tavi’ as moderately susceptible, whereas ‘Bara’ and IPB genotypes (‘Anies’, F8 012328-6-2-1-1-3-1, and F10-074-2-1-B) showed a highly susceptible response to PYLCD. This susceptibility was supported by the logistic regression model, which demonstrated rapid disease development starting from the vegetative phase. Generally, symptoms progressed rapidly from mild at 15–22 days after transplanting (DAT) to widespread severe infection at 50–92 DAT, resulting in incidence ranging from 5.8% to 100% and severity from 2.5% to 92.8%. Spatial-temporal distribution analysis revealed that high whitefly mobility drove this rapid and widespread disease spread, despite the low vector population. Consequently, the value of area under the disease progress curve (AUDPC), which described the cumulative disease intensity over time, had a significant negative correlation with flower number, fruit number, and yield weight. The farmers’ survey revealed strong collective behavior patterns, where farmers within the same geographic area tended to apply similar cultivation practices. This was driven by the intensity of information and idea exchange among farmers, leading to the formation of communal attitudes and practices. Although farmers individually possessed an adequate understanding of PYLCD, the implementation level of integrated disease management remained low. This low implementation significantly influenced the dynamics of the disease pyramid and persistence of the PYLCD epidemic in central of Java.

Cabai (Capsicum spp. L.) adalah komoditas hortikultura strategis di Indonesia. Penyakit daun keriting kuning cabai (PYLCD) telah menyebabkan kerugian besar bagi petani cabai di Indonesia, termasuk di sentra produksi di Jawa bagian tengah. Penyakit ini disebabkan oleh infeksi Begomovirus dan ditularkan oleh kutukebul, Bemisia tabaci, secara persisten dan sirkulatif. Penelitian ini memiliki dua tujuan utama, (1) mengkarakterisasi performa beberapa genotipe cabai dan menganalisis perkembangan PYLCD di lapangan serta (2) mengidentifikasi dan menganalisis praktik budidaya yang dilakukan petani yang berpotensi menjadi faktor epidemi PYLCD di Jawa bagian tengah. Dalam percobaan lapangan, enam genotipe cabai ditanam di Ngablak, Magelang, Jawa Tengah dengan rancangan acak lengkap dalam tiga ulangan. Sementara itu, survei petani melibatkan 24 responden dari Brebes, Magelang, Temanggung, dan Kulon Progo. Wawancara dilakukan menggunakan kuesioner kuantitatif dan deskriptif untuk mengetahui pengetahuan, sikap, dan praktik (PST) petani terhadap PYLCD dan implementasi pengelolaan penyakit terpadu. Pengamatan penyakit, deteksi, dan identifikasi virus dilakukan pada pertanaman di percobaan lapangan dan pertanaman petani di Temanggung. Studi ini mengonfirmasi status epidemi PYLCD di Jawa bagian tengah yang ditandai dengan tingginya insidensi penyakit di lokasi percobaan lapangan dan survei petani. Deteksi virus dengan metode polymerase chain reaction berhasil mengidentifikasi spesies Begomovirus yang dominan, yaitu virus Pepper yellow leaf curl Indonesia virus, Pepper yellow leaf curl virus, dan Tomato yellow leaf curl Kanchanaburi virus. Varietas komersial ‘Asmoro 43-pnc’ diklasifikasikan sebagai tahan, ‘Sios Tavi’ agak rentan, sedangkan ‘Bara’ dan genotipe cabai IPB (‘Anies’, F8 012328-6-2-1-1-3-1, dan F10-074-2-1-B) menunjukkan respons sangat rentan terhadap PYLCD. Kerentanan genotipe tersebut didukung oleh model regresi logistik yang memperlihatkan perkembangan penyakit yang pesat sejak fase vegetatif. Secara umum, gejala penyakit berkembang cepat dari ringan pada 15–22 hari setelah tanam (HST) menjadi infeksi berat yang meluas pada 50–92 HST, menghasilkan variasi insidensi 5,8%–100% dan keparahan 2,5%–92,8% di akhir pengamatan. Analisis distribusi spasial-temporal mengungkapkan bahwa mobilitas kutukebul yang tinggi memicu penyebaran penyakit yang cepat dan meluas tersebut, meskipun populasinya tergolong rendah. Peningkatan keparahan penyakit ini berdampak nyata pada produksi, ditunjukkan oleh korelasi negatif antara nilai area di bawah kurva perkembangan penyakit (AUDPC) terhadap jumlah bunga, buah, dan bobot panen. Survei lapangan mengungkapkan adanya pola perilaku kolektif yang kuat, di mana petani dalam satu wilayah geografis cenderung menerapkan praktik budidaya yang seragam. Hal ini didorong oleh intensitas pertukaran informasi dan gagasan antarpetani, yang menyebabkan terbentuknya sikap dan praktik komunal. Meskipun petani secara individual memiliki pemahaman yang memadai mengenai PYLCD, tingkat implementasi pengelolaan penyakit terpadu masih rendah. Rendahnya implementasi ini berpengaruh terhadap dinamika piramida penyakit dan keberlanjutan epidemi PYLCD di Jawa bagian tengah.