Durian Grower's Tips – Agroharta Fertilizer Sdn. Bhd.

1. Why my durian trees have many flowers but not able to form fruit?

• Reasons:
• Too wet caused by overwatering or raining. When raining, too much of water will be brought up to plant. High amount of water reaching to flower and cause most flowers drop off.
• If plant overdosed on Nitrogen fertilizer (from either high-N fertilizer or high dose of compost/organic fertilizer, durian tree will absorb high amount of water together with Nitrogen during raining or overwatering condition. Such condition will cause the flower drop easily.
• Deficiency of nutrients such as Phosphorus & Boron. Phosphorus is a vital nutrient involved in stimulating and enhancing bud development, seed formation and blooming. Boron increases flower production and retention, pollen tube elongation, and seed and fruit development. Deficiency of B can cause incomplete pollination.
• Solutions:Reduce irrigation and avoid high Nitrogen of fertilizer during preparation of flowering.Nisol 10-50-10+TEFoliar spray at dosage of 2-4g per L of water.Quick absorption to prepare plant with sufficient nutrients, especially Phosphorus that needed during flowering.
• NiCalBo 15.5-0-0+26Cao+2BApply 0.5-1.0kg per tree during preparation of flowering.B helps to improve pollination and Ca helps to strengthen the plant during flowering.

2. Why my durians tend to crack easily during maturing and harvest?

Reasons:

• Too much of rain during fruit development. If frequent rainfall occurs during the rapid fruit expansion period, the water transported by the root system to the fruit will increase rapidly, and the pulp cells will rapidly expand. At this time, the husk is mostly aging, and the husk cells are slow to expand due to the restriction of the cuticle. Irregular water uptake going from very dry to very wet plays a major role in fruit cracking.
• Overdosed of Nitrogen or/and Potassium. Overdosed of Nitrogen caused higher amount of water been carried to durian tree and fruits, with sudden wet and hot weather plus high humidity, the durian fruits tend to crack easily. The antagonistic relationship between potassium and calcium in plant tissue is well documented. When durian trees contain high concentrations of potassium, foliar or soil applications of calcium are ineffective at producing the desired crop response.

Uderdosed of Calcium or/and Boron. Why Ca is difficult to manage?- Ca is immobile nutrient and do not redistribute within the plant. Ca does not move to areas of active growth. Deficiency symptoms show up in the new growth first and most end part of fruit.- Ca needs to be supplied continuously to make sure each part of active growth especially fruit will get sufficient ca.- Ca strengthens the cell wall but it needs to be supported by sufficient binder nutrient such as Boron or Silicone.- Most Ca fertilizer comes with form of either too fast to dissolve or too low/slow in solubility, it reduces the efficiency of Ca absorption to plant.- Fruit cracking also can happen with combination of few reasons.Solutions:

• Sulka- Contains 4 nutrients that needed for fruiting specially to avoid fruit cracking; Potassium for better fruit size, Mg for better photosynthesis, Ca for better fruit wall cell, S for better fruit aroma.- Fully soluble; consist partially quick available nutrients and partially slow released for longer effect. It provides sufficient quick Ca and long-term Ca supply.
• NicalBo- Ca strengthens the fruit cell wall and reduces the risk of fruit cracking. Additional B playing role like glue binding the cell wall to make sure the fruit is stronger to avoid crack.- Fast dissolved to supply quick Ca & B during peak growth of fruits.

3. How to make my young durian trees produce fruit that taste like old trees?

• Sulfur is especially important, as it forms organic compounds within the plant that ultimately contribute to the flavor of durian fruits.
• Volatile sulfur compounds (VSC) are often responsible for better aroma and color of durian fruits.
• Sulfur is also a structural sub-component of amino acids, proteins and many micronutrients and is essential to the production of chlorophyll.
• Sulfur is not very mobile within the plant and so it needs to be supplied in the form of soluble and continuously form.
• Sulka:- Organic certified and comes from natural source.- High content of 48% of Suphate that readily available to plants.- Fully soluble; consist partially quick available nutrients and partially slow released for longer effect.

4. Any more sustainable method to control Phytophthora on my durian trees?

• A better way is to increase the tree’s own defenses and thereby allowing susceptible plants to survive within Phytophthora.
• It is important to note that there is no treatment that will eradicate Phytophthora, so a more sustainable and cost-effective method can be considered.

Solution:

• Fosfika:- Fully systemic, providing protection of the entire plant.- Unique upward and downward systemic activity to protect the entire plant.- Stimulates plant disease defense mechanisms; producing compounds like phytoalexins (antibody) which are toxic to pathogens.
• Formation of necrotic zones (programmed cell death to limit pathogen spread), production of plant hormones involved in defense, production of defense lytic enzymes, and thickening of cell walls.
• Use Fosfika as foliar fertilizer at a dose of 2-3 ml / liter water.