以煙燻水或甲殼素防治番木瓜果實炭疽病及果疫病

Control of Anthracnose and Phytophthora Fruit Rot Diseases on Papaya Fruits by Smoke-water or Chitosan

炭疽病及果疫病是番木瓜果實採後主要病害。本研究的目的是評估煙燻水或甲殼素在水瓊脂培養基及接種在番木瓜果實，評估其對Colletotrichum gloeosporioides及Phytophthora sp.病菌引起的番木瓜果實炭疽病及果腐病的防治效果。以0%、1%、2%、3%、4%、5%、6%、7%及10%煙燻水或0.5%、1.0%、1.5%及2.0%甲殼素配製水瓊脂培養基，試驗結果顯示，煙燻水或甲殼素可顯著抑制C. gloeosporioides及Phytophthora sp.菌體的生長。10%煙燻水處理可完全抑制C. gloeosporioides，而5%－10%煙燻水則可完全抑制Phytophthora sp.；另2%甲殼素則可抑制兩者生長，對菌絲的抑制隨煙燻水或甲殼素濃度提高而增加。此外，番木瓜果實接種C. gloeosporioides或Phytophthora sp.後，以10%煙燻水、20%煙燻水、0.5%甲殼素及0.5%甲殼素加10%煙燻水混合液或水（對照）處理。10%煙燻水、0.5甲殼素或兩者混合液處理可減少番木瓜果實炭疽病及果疫病的損傷直徑及發生率。但0.5%甲殼素包覆之效果仍為最佳，甲殼素及煙燻水之間對兩真菌控制並無協同作用，這些結果顯示甲殼素有效控制番木瓜果實貯藏期間由Colletotrichum gloeosporiodes及Phytophthora sp.引起的炭疽病及果疫病，並延緩感染及減慢感染流程。 The effects of smoke-water or chitosan on anthracnose [Colletotrichum gloeosporioides (Penz.) Sacc.] and Phytophthora fruit rot disease, the major postharvest diseases in papaya fruit, were investigated both in vitro and in vivo culture. In vitro studies showed that smoke-water or chitosan significantly inhibited fungal growth of both C. gloeosporioides and Phytophthora sp. and mycelial growth decreased with increasing smoke-water (from 1% to 10%) or chitosan (from 0.5% to 2%) concentration. Mycelium growth of C. gloeosporioides was completely inhibited with 10% smoke-water treatment, while Phytophthora sp. was completely inhibited with 5%-10% smoke-water treatment. The growth of both fungal pathogens was inhibited with 2% chitosan. For in vivo studies, papaya fruits were inoculated with C. gloeosporioides or Phytophthora sp. and then treated with water only (control), 10% smoke-water, 20% smoke-water, 0.5% chitosan, a combination of 0.5% chitosan and 10% smoke-water. The 10% smoke-water, 0.5% chitosan or the combination of 0.5% chitosan and 10% smoke-water treatment reduced the lesion diameter and disease incidence of anthracnose and Phytophthora fruit rot disease on papaya fruits. However, chitosan and smoke-water had no synergistic effect on the control of anthracnose or Phytophthora. Furthermore, the 0.5% chitosan coating was more effective than the other treatments. Results show that chitosan can effectively control anthracnose and fruit rot disease, caused by C. gloeosporioides and Phytophthora sp., on papaya fruits during storage, possibly by delaying the onset of infection and thus slowing the infection process.