Durian and Phytophthora: an integrated soil and drainage approach

How do soil and drainage fit into Phytophthora management in durian?

Phytophthora is a water-driven disease, and that single fact shapes everything about managing it in durian (Durio zibethinus). The pathogen thrives in wet, poorly drained, compacted soil, and its spores move and infect in standing water. Improving drainage, building soil health and removing the standing water the pathogen needs are part of how growers facing Phytophthora pressure keep their trees healthier, within a wider management programme. None of these is a treatment, and outcomes depend on integrated management rather than any single input. This article sets out the soil and drainage side of that programme, the foundation good orchards build on.

Disease-management note: the practices described here support tree health and reduce the wet conditions that favour Phytophthora. They do not control, cure or stop the disease. Phytophthora management in durian is integrated, combining drainage, sanitation, resistant or tolerant planting material, registered phosphonate-based treatments applied on professional advice, and orchard hygiene. Always follow local agronomic and regulatory guidance.

Why is Phytophthora a water and soil problem?

Phytophthora species, including those that cause durian trunk canker and root and patch rots, are water moulds (oomycetes). Their motile spores need a film of water to move and infect, so the disease intensifies where soil stays wet: low spots, compacted zones, heavy soils with poor structure, and orchards without functioning drainage. Splashing rain and run-off carry spores from infested soil onto trunks and roots. Manage the water and you remove much of what the pathogen relies on, which is why drainage sits at the centre of integrated programmes (Guest et al., 2004; Singh et al., 2025).

What does the soil and drainage foundation look like?

Get the water off and through

The first priority is that water moves away from the root zone and the trunk base rather than pooling there.

• Shape the land and cut drains so surface water leaves the orchard, especially in low spots.
• Plant on mounds or raised beds in heavy or wet ground so the root collar sits above the waterline.
• Relieve compaction, which traps water and deprives roots of oxygen, weakening the tree.

Build soil structure and biology

Well-structured, biologically active soil drains better and supports a more resilient tree.

• Raise organic matter and improve aggregate structure so water infiltrates rather than ponds. A humic soil conditioner such as SoilBoost EA may support soil structure and cation exchange capacity as part of this, helping the soil hold nutrients; it is not a disease treatment.
• Maintain ground cover and cover crops between trees to cut erosion and run-off and to limit rain splash of soil onto trunks.

Keep the orchard clean

• Remove and dispose of infected material and fallen fruit that can harbour the pathogen.
• Avoid moving infested soil on machinery and boots between blocks.
• Keep trunk bases clear and dry; mulch should not be piled against the collar.

Where do treatments fit?

Soil and drainage management is the foundation, but it works alongside, not instead of, the rest of an integrated programme. Registered phosphonate-based treatments are widely used against Phytophthora in durian; use them on professional advice and according to local registration. Resistant or tolerant rootstocks and planting material, careful irrigation that avoids overwatering, and prompt attention to early trunk lesions all sit in the same integrated picture (Guest et al., 2004).

Frequently asked questions

Will better drainage cure Phytophthora in my orchard? No. Drainage and soil health support tree health and reduce the wet conditions the pathogen needs, but they do not cure or stop the disease. Management is integrated and ongoing.

Does a soil conditioner treat the disease? No. SoilBoost EA may support soil structure and a healthier root environment. It is not a fungicide and makes no disease-control claim.

What is the single most important soil measure? Drainage. Phytophthora depends on standing water to move and infect, so getting water off and through the soil removes much of what the pathogen relies on.

Talk to an agronomist

Soil and drainage are the foundation for orchards facing Phytophthora pressure, and they are where Chemiseed can help most. To build a soil-health and drainage plan for your orchard, request a quote or talk to a Chemiseed agronomist on WhatsApp at +60 17-237 4058. For diagnosis and treatment decisions, work with a qualified plant pathologist and follow local registration.

This article is for general agronomic information and is not a disease-treatment recommendation. Outcomes depend on integrated management.

Sources

• Guest, D.I., Chau, N.M., Sangchote, S., Vawdrey, L.L. & Diczbalis, Y. (2004). Integrated management of Phytophthora diseases of durian: recommendations and benefit-cost analysis. pp. 222-226 in: Drenth, A. & Guest, D.I. (eds), Diversity and management of Phytophthora in Southeast Asia. ACIAR Monograph No. 114. https://era.dpi.qld.gov.au/id/eprint/10666/
• Singh, A., Chow, C., Nathaniel, K., Vun, Y.L., Javad, S. & Jabeen, K. (2025). Management of Phytophthora and Phytopythium oomycete diseases in durian (Durio zibethinus). Crop Protection 190: 107086. https://www.sciencedirect.com/science/article/abs/pii/S0261219424005143

SoilBoost EA is a soil conditioner. It is not a fungicide, pesticide, plant protection product, or standalone treatment for Fusarium TR4, Phytophthora, or any crop disease. It may support soil structure and root-zone conditions as part of a broader agronomy program, but disease management must follow local agronomist, regulatory, sanitation, drainage, and resistant-variety guidance.