Occurrence and Control Methods of Jackfruit Stem-End Rot and Fruit Rot
The African giant snail, also known as the French snail, is a pest that harms pineapple. It mainly bites the base of the fruit from June to August when the fruit is ripe, leaving holes of varying depths, which makes the pineapple prone to infection by pathogens and rot, thereby reducing the commercial value of the fruit and even making it inedible. Control methods: (1) Manual capture. In the African giant snail...
I. Jackfruit Stem-End Rot This disease often causes massive fruit rot during the fruit ripening period and during storage and transport. The incidence rate is generally 10%-20%, and can reach 30%-40% in severe cases. Affected fruits usually show symptoms starting from the stem end. The lesions initially appear as pinhead-sized brown spots, which gradually expand into large circular lesions that are dark brown in the center and grayish-brown and water-soaked around the edges. Eventually, most of the fruit turns brown and rots, and the flesh deteriorates and tastes bitter, losing its edible value. The diseased area is densely covered with a white sticky substance, which is the conidial mass of the pathogen.Jackfruit stem-end rot is a fungal disease caused by the pathogen Lasiodiplodia theobromae. The conidia are initially colorless and single-celled, later becoming brown and two-celled, with longitudinal striations on the surface, oval to elliptical in shape. The jackfruit stem-end rot pathogen is a fungus with relatively weak parasitic ability.
The pathogen overwinters as mycelium and pycnidia on diseased branches and diseased fruits. In the spring of the following year, when climatic conditions are suitable, it produces large numbers of conidia as the primary infection source, infecting young jackfruit fruits. Because young fruits have strong disease resistance, the pathogen remains latent inside the fruit after invasion, and symptoms appear one after another when the fruit begins to ripen and its disease resistance declines. In addition, the pathogen also invades through wounds. Fruit surface injuries caused by typhoons or insect damage during the fruiting period are important routes of pathogen invasion. The key measure for controlling this disease is to spray fungicides for protection during the young fruit stage, especially intensifying fungicide protection after typhoon rain. The main fungicides include: 70% thiophanate-methyl wettable powder at 800 times dilution, 40% copper oxychloride suspension concentrate at 500 times dilution, 75% chlorothalonil wettable powder at 800 times dilution, and 1% Bordeaux mixture. Secondly, during production management and harvesting, fruit injuries should be minimized as much as possible. During storage and transport, it is best to wrap each fruit individually in paper to prevent diseased fruits from touching each other and increasing transmission.
II. Jackfruit Fruit Rot Jackfruit fruit rot is a common disease that mostly occurs during the fruit ripening period and during storage and transport. The diseases causing jackfruit fruit rot, besides anthracnose, also include jackfruit soft rot, jackfruit pink mold rot, and jackfruit sour rot.
1. Jackfruit Soft Rot It can harm inflorescences, young fruits, and ripe fruits, but ripe fruits are most susceptible. The diseased area initially appears water-soaked and quickly expands into brown soft rot. The surface of the diseased area is covered with white coarse hairy sporangiophores and small black granules -- sporangia.
2. Jackfruit Pink Mold Rot It often harms fruits together with the stem-end rot pathogen and Rhizopus, causing brown rot in the later stage of the fruit. The surface of the diseased area has a layer of mold, initially white and later light pink.
3. Jackfruit Sour Rot The affected part of the fruit turns brown and soft, with a layer of white mold on the surface. The interior of the fruit quickly turns brown and soft-rots, with juice flowing out and emitting a sour odor.
The above three diseases are all caused by fungal infection. The pathogenic fungus of jackfruit soft rot is Rhizopus stolonifer, whose mycelium is vigorous and rhizoids are well developed. The pathogenic fungus of jackfruit pink mold rot is Trichothecium roseum. The mycelial layer on the diseased area is initially white and later pink. The conidia are colorless, two-celled, and oval. The pathogenic fungus of jackfruit sour rot is Geotrichum candidum. The diseased area of the fruit produces large amounts of white mold, whose hyphae break into chains of arthrospores, colorless, initially rectangular and later oval, with bluntly rounded ends.
The above three pathogens are all weak parasites, and their infection has two common characteristics: First, they only infect the growth stages of the host with relatively weak disease resistance. Therefore, all three diseases mainly harm ripe fruits and generally rarely harm green fruits, because green fruits have stronger resistance. Second, they generally can only invade the host through wounds or natural openings. Therefore, the occurrence of the diseases is closely related to the wound conditions on the fruit surface. During transport, diseased fruits can infect each other through contact.
Therefore, to control the three types of fruit rot, attention should be paid in the field to controlling insect pests that harm the fruit, harvesting should be done carefully, and fruit injuries should be avoided as much as possible during transport. After harvesting, the fruits should be soaked in 40% thiabendazole suspension concentrate at 500-800 times dilution for 5-6 minutes. After drying, wrap each fruit individually in paper to prevent the pathogen from spreading through mutual contact.