EPIDEMI PENYAKIT BUSUK PANGKAL BATANG LADA DI PROVINSI SULAWESI TENGGARA

LA ODE SANTIAJI BANDE, Prof. Dr. Ir. Bambang Hadisutrisno, DAA

2012 | Disertasi | S3 Fitopatologi

Penyakit busuk pangkal batang lada yang disebabkan oleh Phytophthora capsici, telah menyebar luas di Provinsi Sulawesi Tenggara. Intensitas penyakitnya sebesar 45,7% pada tahun 2010, meningkat menjadi 61,2% tahun 2011. Penyakit di lapangan membentuk agihan mengelompok yang menunjukkan bahwa patogennya merupakan patogen terbawa tanah. Intensitas penyakit tertinggi terdapat di Kabupaten Konawe. P. capsici isolat lada asal Provinsi Sulawesi Tenggara mempunyai variasi dalam tipe koloni, bentuk, dan ukuran sporangium. Virulensinya tinggi yakni mampu menginfeksi daun lada (Piper nigrum), sirih (Piper betle), dan durian (Durio zibethinus), tetapi tidak dapat menginfeksi daun cabai (Capsicum annuum) dan rough lemon (Citrus jambhiri). Perkembangan penyakit busuk pangkal batang lada bervariasi pada berbagai kondisi agroekosistem. Perkembangan penyakit model Gompertz terdapat di pertanaman lada yang gulmanya banyak dan tanpa memperhatikan gulmanya, model logistik terdapat di pertanaman lada yang gulmanya sedikit, dan model monomolekular terdapat di pertanaman lada yang gulmanya banyak yang hanya terdapat di Kabupaten Kolaka. Laju perkembangan penyakit terendah terdapat pada agroekosistem lada yang gulmanya banyak. Hasil analisis lintas diketahui bahwa epidemi penyakit busuk pangkal batang lada didukung oleh kondisi cuaca dan sifat fisika dan kimia tanah. Unsur cuaca yang secara langsung menyebabkan peningkatan laju epidemi penyakit busuk pangkal batang lada di setiap daerah bervariasi dan unsur yang paling dominan adalah curah hujan. Peningkatan laju epidemi penyakit di Kabupaten Konawe Selatan disebabkan oleh peningkatan curah hujan dan lengas tanah, di Kabupaten Konawe oleh curah hujan dan suhu udara, sedangkan di Kabupaten Kolaka oleh suhu udara, jumlah hari hujan, dan curah hujan. Sifat fisika dan kimia tanah yang menyebabkan peningkatan penyakit busuk pangkal batang lada adalah kenaikan fraksi lempung, fraksi pasir, porositas, C-organik, N total, dan salinitas, sedangkan yang menurunkan adalah lengas tanah pada pF 2,54, unsur P tersedia, K tersedia, KPK, KB, Ca tertukar, Mg tertukar, K tertukar, rasio C/N, dan potensial redoks. Inokulum P. capsici dalam tanah di pertanaman lada dapat dideteksi dan dihitung kerapatannya dengan menggunakan umpan daun lada. Persamaan untuk menggambarkan hubungan antara persentase potongan daun terinfeksi (Y) dengan kerapatan inokulum (X) adalah Y = 18,02 + 14,67X, (X: log10). Peningkatan intensitas penyakit busuk pangkal batang lada sejalan dengan peningkatan kerapatan inokulum P. capsici dalam tanah. Kerapatan inokulum P. capsici dalam tanah di pertanaman lada semakin menurun setelah intensitas penyakit mencapai kategori sangat berat (puso).

Black pepper foot rot disease caused by Phytophthora capsici is widely spread in the Province of South-East Sulawesi. In 2010, the intensity of this disease reached 45.7% which then increased to 61.2% in 2011. The disease in the field was distributed in patch, which shows that the pathogen is a soil-borne pathogen. The highest intensity of the disease occurred in Konawe District. The P. capsici isolates of black pepper varied in the colony type, shape, and size of sporangium. P. capsici was highly virulent and therefore it was able to infect black pepper (Piper nigrum) leaves, betel (Piper betle), and durian (Durio zibethinus) but unable to infect pepper leaves (Capsicum annuum) and rough lemon (Citrus jambhiri). The development of the black pepper foot rot disease varied according to the condition of each agriculture ecosystem. The disease development of the Gompertz model was found in black pepper plantation by considering and without considering the abundance of weeds. The development of disease of the logistic model was found in black pepper plantation with few weeds. The monomolecular model in black pepper plantation with abundant weeds was found only in Kolaka District. The lower infection rate of the disease was found in an agriculture ecosystem with abundant weeds. The results of path analysis shows that the contributory causes of foot rot epidemic on black pepper are weather condition and the physical and chemical characteristics of the soil. The weather elements directly causing the epidemic progress of foot root varied in each region and the most dominant weather element was rainfall. The increase of the epidemic rate in South Konawe District was caused by the increase in rainfall and soil moisture. In Konawe District, it is caused mainly by rainfall and air temperature, in Kolaka District it is caused by the number of rainy days, rainfall, and air temperature. The physical and chemical characteristics of the soil which increased the intensity of foot rot on black pepper were clay fractions, sand fraction, porosity, C-organic, total N, and salinity, whereas soil moisture (pF 2.54), available phosphor, available potassium, CEC, base saturation, Ca exchangeable, Mg exchangeable, K exchangeable, C/N ratio, and redox potential decrease disease intensity. The P. capsici inoculum in the soil on the black pepper plantation can be detected and their density quantified by leaf-baiting. The equation to represent the relation between the percentage of infected leaf chips (Y) and the density of inoculum (X) was Y = 18.02 + 14.67X, (X: log10). The increase in disease intensity occurred in parallel with the greater density of P. capsici inoculum in the soil. The density of P. capsici inoculum in soil tended to decline when the disease intensity reached the highest level.

Kata Kunci : penyakit busuk pangkal batang lada, epidemi, cuaca, tanah, umpan daun