The care of longan tree as regards to its planting position, soil requirement, its watering needs, fertilization, pests and diseases are discussed below.
Position for Longan Tree: Where to Plant Longan Tree
- Select the driest and hottest area of the farm/garden, which does not remain wet for long time.
- The tree is not tolerant to excessively wet or flooded soil conditions and it may die due to constantly wet soil conditions.
- Plant the longan tree quite away from the lawn because the roots of the mature tree spread beyond the drip-line and heavy lawn fertilization may reduce fruiting and or fruit quality.
- Plant away from the lawn as the lawn mower if accidentally damages the trunk of the tree can reduce fruiting or even the tree may die.
Soil for Longan Tree
- Longan tree can grow on well drained various soil types including sand, sandy loams, calcareous and rocky soils.
- Keep the area around the trunk of the longan tree free from grass and weed.
- Apply a 10 cm (4 inch) layer of bark, wood chips or similar mulch material spreading to the drip-line from 12 inch of the trunk. It will protect the trunk from rot and suppress weeds and hold soil moisture.
Watering Longan Plant
- Keep the soil of the young tree moist. When the tree starts to produce flowers, water regularly till it bears fruit.
- Excessive rains during flowering may cause flower drop and reduce pollination.
- Established trees should be irrigated regularly from the signs of blooming appear and until harvest.
- The use of sprinklers on a timer may result in over watering, causing root rot and decline.
- Warm and rainy winters encourage vegetative growth and reduce flowering.
Fertilization Longan Tree
During the immature stage, a combination of organic may be used. Organic fertilizer such as cow manure can be applied at the rate of about 10 kg/tree/year, applied about 3-4 times in a year.
- The longan tree requires equal ratio N:P:K fertilizer (i.e. 6:6:6 or 15:15:15, etc.). Spread the fertilizer on the soil, 10 inches from the trunk, and spread it out 1 foot beyond the drip-line. Water well after applying.
- First year of planting: After one month of planting, fertilize with about 110 g (1/4 pound) of 5-5-5 NPK fertilizer every 2 months.
- Second Year: Fertilize with about 220 g (1/2 pound) every 3 months.
- Third year: Fertilize with about 450 g (1 pound) every 3 months.
- Mature Longan Trees: Mature longan trees require 1.5 to 2.25 kg (3.3 - 5 pound) of fertilizer just before the tree blooms in late spring and again before or during the harvest.
- If the soil is acid to neutral, apply iron sulfate at 5 to 30 g per tree to the soil 3 to 4 times a year.
- Do not fertilize your longan tree during the winter, specially organic nitrogen containing fertilizer as this will encourage growth during the winter and reduce flowering in the spring.
Pruning of Longan Tree
- You can prune the longan tree after harvest to control its height and spread. Trees more than about 10 to 15 ft high (3 - 4.5m) and 15 to 30 ft (4.5 - 9 m) wide are difficult to care.
- Cutting 1 to 2 inches from the tips of new shoots on the young longan tree during the spring and summer will help keep the tree compact.
- Bend long upright branches to a horizontal position by tying to keep the tree at a lower height.
- Pruning longan tree in winter will reduce flowering in the spring.
- For immature tree, only limited numbers of main branches are retained to obtain the desired structure. In China, one strong branch is retained after every growth flush to form a natural round-shaped crown of 6 to 10 main branches.
Insects and Pests
The most common pests on the longan tree are the lychee webworm and several scale insects. The lychee webworm attacks emerging shoots and panicles, flowers and young fruit and if left uncontrolled drastically reduce fruit set and crop yields.
Scales insects like banana shaped (Coccus acutissimus) and barnacle (Ceroplastes spp.) are other common pests that attack the longan tree, mostly the underside of leaves and the philephedra scale (Phillephedra tuberculosa) attacks leaves and fruit.
Bats or flying foxes can eat up longan fruits during fruiting seasons. A protective net around the perimeter of the tree can be erected.
Scales insects like banana shaped (Coccus acutissimus) and barnacle (Ceroplastes spp.) are other common pests that attack the longan tree, mostly the underside of leaves and the philephedra scale (Phillephedra tuberculosa) attacks leaves and fruit.
Bats or flying foxes can eat up longan fruits during fruiting seasons. A protective net around the perimeter of the tree can be erected.
Diseases
- The longan tree is free from major disease problems.
- During high humidity, warm and rainy weather, the limbs, bark and leaves are attacked by Red alga (Cephaleuros virescens), which produce dark gray to reddish-rust colored spots and patches.
- In severe infections, leaf drop and stem die back occur.
- Parasitic lichen (Strigula sp.) may produce white star-shaped spots on leaves which reduces their photosynthesis ability.
