Instructions for flower pruning, fruit pruning and additional pollination for durian

Flower pruning, fruit pruning and additional pollination determine the number of fruits, fruit location and uniformity of the durian orchard. Instructions on choosing flower clusters, pollinating at night, pruning fruit according to tree strength and avoiding overloading the tree.

Summary: A lot of durian flowers does not mean there will be a good crop. If the flowers are too dense, have poor pollination, or keep the fruit in the wrong position, the tree will easily lose fruit, become distorted, break branches, and decline after harvest. This article guides three consecutive operations: pruning flowers to concentrate flowering, additional pollination to increase fruit set, and pruning fruit to keep the yield within the tree's capacity.

Applies to: Durian Ri6, Dona, Monthong, Musang King in business orchards.
Duration: From flower formation to 45-60 days after fruit set.
Difficulty level: Advanced. Need to do it at the right time, especially pollination at night.
Estimated additional costs: 5-20 million VND per hectare per crop depending on pruning and pollination work.

Why do we have to prune flowers

Pruning flowers helps:

Reduces nutrient competition.
Helps remaining flowers develop evenly.
Concentrate fruit on strong branches, close to the trunk.
Reduces young fruit loss in the future.
Preserve plant strength for the next crop.

Without pruning flowers, the tree can produce a lot of flowers but the fruit set rate and fruit quality are low.

Prune flowers

Choose flower position

Prioritize keeping flowers:

On strong level 1 and level 2 branches.
Location near main body.
The branches are large enough in diameter, pest-free.
The flower clusters are evenly distributed around the canopy.

Should be removed:

Flowers at the tip of the branch are weak.
Flowers close to the top, small branches.
The flowers in the canopy are too dense.
Deformed flowers, pests, blooming too far from the main bloom.

Flower density

There is no fixed number for every tree. Principle:

Healthy trees retain more than newly recovered trees.
Small branches keep little.
Do not let the flower cluster get too thick at one point.
Keep the flowers in each layer of branches so that the fruit will be distributed evenly in the future.

Pruning flowers should be done gently several times rather than too harshly once.

Additional pollination

When to pollinate

Additional pollination is necessary when:

The orchard has few pollinating insects.
Rain, humidity or wind make powder worse.
Want to increase fruit set rate in high value shipments.
The variety has a low natural beaning rate.

Durian usually blooms in the evening to night, so pollination must be done at the right time.

Time

Do it at night, when the flower blooms and the pistil is ready to receive pollen.
Choose healthy flowers that won't get wet in the rain.
Avoid handling during heavy rain or sick flowers.

How to do

Collect pollen from suitable male flowers/blooming flowers in the orchard or other plants of the same variety if available.
Use a soft brush to gently brush the powder onto the stigma.
Manipulate gently, do not break the flower stem.
Mark the pollinated area to monitor the fruiting rate.

If using pollen from a different variety, make sure the pollen source is disease-free and suitable for hatching time.

After fruiting

After young fruit forms:

Keep water stable.
Do not let the tree grow strongly.
Pest prevention on young fruit.
Monitor physiological loss.

The next 2-4 weeks, the beans are very sensitive. Water shock, lack of nutrition or pests all cause fruit to drop.

Prune fruit

Phase 1

When the fruit was still small:

Discard misshapen and diseased fruit.
Remove fruit from weak branches and branch tips.
Avoid fruit growing too close together.

Phase 2

When the fruit gets bigger, the shape is clearly visible:

Keep the fruit evenly round and have strong stems.
Distribute fruit evenly around the canopy.
Don't let one branch carry too much.
Prioritize fruit that is close to the stem, easy to raise.

Phase 3 if necessary

When the tree shows signs of overload:

Yellow leaves, falling off.
Strong sagging branches.
Fruits develop unevenly.
The tree's buds compete with the fruit.

More pruning is recommended to save the quality of the fruit lot and preserve the tree's strength.

Keep the number of fruits according to the tree's strength

Evaluate tree strength by:

Thickness of leaves.
Leaf color and leaf age.
Root strength.
Yield history of previous crops.
Diameter of fruit-bearing branch.

Trees that have just recovered from a heavy crop should not maintain high yields. A healthy tree with many leaves and good roots can keep more but still must be distributed properly.

Common mistakes

Leaving too many flowers: the plant loses strength and bears fruit unevenly.

Pollination at the wrong time: ineffective pollination, a lot of effort but low success rate.

Keep fruit at the tip of weak branches: branches easily break, small fruit, poor quality.

Unfortunately the deformed fruit: will still have to be discarded or sold at a low price in the future.

Not pruning according to the tree's strength: the tree is overloaded, the fruit is shabby, and it declines after autumn.

Monitor and record

[ ] Days of pruning flowers in batches.
[ ] Additional pollination areas and pollen sources.
[ ] Fruit setting rate after 7-14 days.
[ ] Number of fruits retained by tree group.
[ ] Rate of fruit distortion, falling, pests and diseases.
[ ] Yield and quality after harvest.

Recording each group of plants helps you decide how many flowers/fruits you can keep next season.