Each variety of longan requires different time for the Process of fruit formation and development from anthesis until harvesting. The shorthest time for the process was observed on cv. diamond river and pingpong, which needs 4,5 month while other varieties need 5-6 month. Fruits morphology and physiology change during the process.
Ready to harvest fruits are indicated by several characters, which are; smooth, soft and brown fruit peel, soft and aromatic aril. The problem found when the time for harvesting is approaching is the bat attack, which could make failure on harvest. The bats attack at the process of aril thickening, which occurred 1 month before harvesting. The signal of aril thickening phase is the change of seed colour to brown from white.
Bats is the main prime of pest in longan cultivation, the harvest will fail if they couldn’t be stop. The fruits will lose if we do not anticipate it before. There are some techniques to anticipate fruit lost. :
Arrange the period of longan harvesting is around the same time with that of other fruits
This technique can be done with two ways :
- Technology of flowering induction with KClO3. With this technology we can make a plan to arrange the time of harvesting is similar to that of other fruits around longan field.
- Planting hedge crops. This technique purpose is to allure the bats to the hedge crops instead of the longan.. The example of hedge crops is sawo.
The majority of Indonesia’s farmer use this technique to anticipate bats attack. There are two kind of fruits wrapping material :
- Material from bamboo. This material can be used until three season if saved well. Before saved, the bamboo wrappings are dried under the sun and hung above to avoid termite. The weakness of this material is that the size is small and is not readily available.
- Material from paranet. This kind of wrapping can be prepared by ourselves. The advantages of using paranet are its low price and can be made in various sizes. The weakness is that the material broken easily due to rain and sunshine.
Bats are usually live in colony, nesting in a cave and flying horizontally. Based on the characters, some of the concerns are:
- The net should be higher than the plant
- The net should be put among the plant and bats nest
- The net material should be thick
Choose materials which have aroma
Aroma from longan fruits allures the bats, therefore to avoid it, it is better to put some substance which have stronger aroma to distract the bats. Some substances that can be used are salty fish or shrimp paste. The substances are put around the fruits panicle to cover the aroma form longan fruits.
The effectivity of the technique depends on the availability of the material, the setting skill and the bat population around the crops. Good luck.
By : Buyung Al Fanshuri
Indonesian Citrus and Subtropical Fruits Research Institute
Indonesian Agency for Agricultural Research and Development