How Healthy is Your Durians?

How can someone tells his/her durian is healthy? There are many ways to consider. It can be seen how 'green' is the leaves and performance of the plants. There is scientific way how to describe this. If your farm is big let say more than 10 acres, it is worth checking the healthiness.

The easiest method is using chlorophyll meter or SPAD meter. Measures leaf chlorophyll, an important indicator of plant health. The latter performs quick measurements of the chlorophyll content of leaves without damaging the leaf.

SPAD readings are recorded by inserting  the newest fully expanded leaf from each plant while avoiding old or immature leaves. Normally the fifth or sixth leaf counted from the shoot was taken where leaf mid-portion was recorded.

As a rule of thumb SPAD reading 50-60 means that the leaves are green and healthy while 30 and below the leaves are yellowish and not healthy.

Reports have shown that there is high correlation between chlorophyll content and SPAD readings.

Green bug on durian leaves

Young durian are proned to insect attack. The common insects are termites, pysllids, borers, grashoppers etc. The green bugs that attack durian leaves are very rare.

I have never seen this green hopper before. It causesdamage to the leaf blade

Problems in Durian Plantation

Observations in durian during this season (March 2019)

a.  Durian flowering intensity are low compared to the same season last year. The flower emergence are much affected and aborted  by the extreme hot weather condition followed by very high sudden showers however, there are occurrence of flowers that anthesised which fertilized and  developed into small sized fruitlets. The total number of trees that flowered during this season was not counted yet to estimate the yield and production . On closer observation at one of those trees that the fruitlets need to be sprayed with foliar fertilizers combine with fungicides and insecticides. There are occurrence of Phytopthora on the fruitlets as shown by which powdery mucilage around the external skin  which need to be treated with Ridomil or Aliette immediately.  

b.    Insect attack. There are occurrence of branch borer attack on some of the durian trees as observed from the death of the branches and twigs.  Close observation of  dead young shoots showed that  insect excreta or fras produced resulted from boring of  branch pith and similar occasion on big branches. The case is quite rare that  the insect borers, Zeuzera  attack other crops like coffee and cocoa.

Immediate treatment need to be taken before it becomes rampant.

i.Prune all dead branches and spray with Rogor.

ii. Big branches which had been bored need to be cleaned and inject with high dosage insecticide of Rogor or Tamaron using syringe into the holes made by borers. During the activity ensure the operators used personal protection equipment (PPE)  such as  googles dan gloves for safety purposes.

Other insect problems is pysllids attack on young shoots that caused  “broom-shaped twigs” that should  tackled immediately using Nurelle 505 .

c 

d   New planting : Watering and composting are  not enough. Some plants are not growing ; no new  shoot growth. Immediate action should to taken to correct the problem. Each plant needs at least 6 litres of  water per day ( 3 litre in the morning and 3 litre in the afternoon). Composts needed to be adequate at 3 kg per plant  and if the soil is high in clay content compost had to be increased to 5 kg per plant.

Durian Water Requirement in Field Planting

The establishment of durian plantation is a big challenge. The first step establishment is proper planning as every aspect has to be taken into consideration. This includes land preparation, planting per se, design of the farm, irrigation, cover crops, shade crops, netting, nursery etc.

One of the most critical factor in establishing durian plantation is irrigation. For a big area let say 50 acres to set up an irrigation system is not as easy. Once the land has been cleared the landscape of the land has to be known. If the land is flat and undulating it is easy to fix the lines . But , if the land is sloopy and hilly than the design is different. This is because water needs the correct pressure to reach at the end of the pipe,therefore no choice TOPOGRAPHIC survey has to be done.   

Slow Death in Durian Seedlings Grafted Plants.

Slow death in durian seedlings when grown in the field can be caused by many factors.The basic principle is that there is no SOURCE and SINK connection meaning that the continuity of the flow is stop. Source is referred to upper part of the plants that include leaves , shoots, twigs, upper stem (above ground)and branches while sink refers to roots, root hair hairs (below in the ground). Both source and sink must be harmonious . Either source or sink is affected , the plants will will be disturbed.

Upper portion of plants can be affected by diseases, insect , mechanical damage , limb breakage. The lower portion i.e. roots will also be affected by disease, insects, nutrient , water deficit etc. If one of these parts are affected then it will affect others in the plants. Meaning that growth will be affected which leads to plant injury, wilting, stress and death.

Sometimes it is very tricky to know what may cause death to the plants as shown . The leave drops slowly andn dry finally dies, 

Examine the roots where disease or something else might disrupt the uptake of water and nutrient

Leaves fall and plants become dry 

Disease occurrence in durian fruits

A farmer is not guaranteed to harvest fruits even there are  a lot of fruits.  The time to take from flowering till maturity depends on variety. Some early harvest clones such as D99 takes about 90 days to harves. D24 takes about 100 days  and most of the clones will takes about 105 to 110 days to harvest. Extra care must given during flowering and fruiting besides water is disease and insect pest control. Common disease is Phytopthora and common pest is black moth.

Fruit caaused by Phytopthora disease

Growth Performances of Durians in Field

To grow durian is not as easy to grow oil palms, rubber or bananas. Durian need extra care especially planting in the field. You can not take things for granted that once you have  planted that's all. Attention must be given for at least every week so that the plant established its growth. Some of the critical factor is water; too much or too little water might affect the growth.  Durian roots may easily rot due too much water particularly in waterlogged condition where water is not drained and stay stagnant. On the other hand, too little water may cause leaves to dry and wither which later wilting takes place. Then, precautions must be taken in dry weather condition such as mulching the plants which means to cover the surrounding areas planted using composts or dry gasses or leaves.