Arabfields, Meriem Senouci, Correspondent, Hanoï, Vietnam — Dong Nai Province stands as Vietnam’s foremost cashew-producing region, where approximately 175,000 hectares of cashew orchards sustain the livelihoods of tens of thousands of farming families across extensive rural landscapes. This vast cultivation area positions the province at the heart of national cashew production, contributing substantially to both local economies and the country’s broader agricultural export portfolio. In recent days, however, unusual meteorological conditions have emerged as a serious concern for growers, particularly as many orchards enter the critical flowering and fruiting stages that determine the success of the upcoming harvest season.

Storms that swept through the province on February 26 and 27, 2026, brought heavy rainfall and shifting atmospheric patterns that have created ideal environments for the rapid emergence and proliferation of various pests and diseases. These weather events, characterized by off-season rains followed by cool, cloudy mornings and intensely hot afternoons, have already begun to affect flowers and young fruits in numerous locations. Scorching daytime temperatures cause cashew nuts to dry out and crack while still attached to the trees, while the combination of moisture and temperature fluctuations exacerbates fungal infections and insect infestations that can quickly diminish potential yields.

Large cashew plantations situated in communes such as Bu Dang, Phuoc Son, Tho Son, Bu Gia Map, Dak O, Nghia Trung, Bombo, Dak Nhau, Binh Tan, Phu Trung, and Phu Nghia now face heightened risks. In these areas, where cashew trees dominate the agricultural terrain, the recent precipitation has left orchards vulnerable during a period when even minor disruptions can lead to substantial losses. Farmers report that the storms arrived precisely when trees required stable, dry conditions to support healthy pollination and fruit development, thereby amplifying the threat posed by opportunistic pathogens.

One family operating nearly 10 hectares of cashew orchards in Binh Tan commune, with trees ranging in age from five to more than 20 years, has expressed deep concern over the sudden weather shift. Their grafted varieties are reaching their first commercial harvest, while older natural trees remain in full bloom and early fruit set, rendering the entire plantation susceptible to fungal outbreaks and insect damage. The two consecutive days of rain have heightened the likelihood of pest proliferation, and without swift remedial action, the family anticipates noticeable reductions in both quantity and quality of the harvest.

Similar anxieties prevail among growers in Phu Nghia commune, where another household managing more than three hectares observed the gloomy, rainy conditions with alarm during the peak flowering phase. Off-season rains and persistent morning cloud cover promote the spread of anthracnose, a fungal disease known to cause flowers to dry prematurely and young fruits to wilt and drop. The family emphasizes that rains coinciding with maximum flowering carry a particularly high risk of yield decline unless pesticides are applied promptly to cleanse the flowers and suppress emerging parasites.

A third family cultivating nearly five hectares in the same commune has maintained a rigorous schedule of pesticide treatments, including four careful applications targeting flowers and developing fruits. Despite these efforts, the capricious weather of recent days threatens to undermine their preventive measures. Dark, cool mornings followed by strong afternoon sunlight have created microclimates that favor the resurgence of pests and diseases, prompting the growers to intensify daily inspections and prepare for immediate intervention should signs of damage appear on flowers or young fruits.

The director of the Regional Agricultural Service Center No. 16 in Dong Nai has provided detailed guidance to help farmers navigate these challenges. Regular orchard inspections remain essential for early detection of problems during the sensitive flowering and fruiting periods. Anthracnose, in particular, thrives under hot, humid conditions accompanied by significant day-to-night temperature variations or foggy weather. The disease typically manifests as dark brown spots on leaves, flowers, and fruits, often surrounded by yellow halos on foliage and sunken lesions on fruits that eventually lead to wilting and desiccation. To combat this fungus, specialists recommend the use of targeted pesticides containing active ingredients such as propineb, hexaconazole, difenoconazole, or specialized mixtures designed for both preventive and curative applications. Orchards not yet infected but exposed to rain or fog should receive protective sprays, while those already showing symptoms require two to three applications spaced at seven- to ten-day intervals to achieve effective control.

Garden bugs represent another persistent threat, as these insects proliferate rapidly and feed on the sap of young leaves, floral stems, and developing fruits, causing tissues to dry, blacken, and ultimately die. Symptoms can sometimes be confused with those of anthracnose, underscoring the need for accurate diagnosis. Control measures involve insecticides based on cypermethrin, abamectin, alpha-cypermethrin, or combinations of buprofezin and imidacloprid. Spraying should occur early in the morning or late in the afternoon under cloudy skies, with applications covering entire areas systematically, beginning at the outer edges and proceeding inward in a spiral pattern to ensure thorough coverage.

Thrips, which tend to conceal themselves within dense, shaded sections of orchards, further complicate management efforts. Effective insecticides for these pests include formulations such as those containing thiamethoxam or other targeted compounds, applied with attention to penetration into hidden habitats. Fruit borers pose additional risks by piercing developing fruits, causing sap leakage that invites secondary fungal infections. High-pressure sprayers directed at fruit clusters can help open calyces and dislodge cocoons, while late-day applications minimize interference with beneficial pollinators. Recommended products for borer control include biological and chemical options suited to late-afternoon timing.

The convergence of these pest and disease pressures, driven by the recent unusual weather, highlights the fragility of cashew production during its most vulnerable growth stages. Cashew trees require consistent environmental conditions to achieve optimal nut development, and deviations such as unexpected rainfall or abrupt temperature swings can cascade into widespread damage across entire plantations. For a province encompassing 175,000 hectares of cashew cultivation, even moderate levels of infestation or fungal spread could translate into meaningful shortfalls in overall output, affecting not only individual farm incomes but also the stability of local processing industries and export supply chains.

Looking ahead, the data emerging from the current situation allow for informed projections regarding future harvests. The observed pattern, whereby short bursts of off-season storms and subsequent temperature fluctuations create favorable conditions for pests and anthracnose, suggests that similar meteorological events, if they recur with comparable frequency or intensity in the coming seasons, will continue to elevate risks during flowering and fruiting periods. Without sustained adherence to expert-recommended monitoring and timely intervention protocols, yield reductions could become more pronounced, potentially compromising up to a significant portion of expected production in affected zones. Over the medium term, repeated exposure to such climatic variability may necessitate expanded adoption of resilient cultivation practices, including improved drainage systems, diversified planting schedules, and greater integration of biological control methods alongside chemical treatments.

Farmers who implement proactive measures, such as regular scouting and strategic spraying aligned with specialized guidelines, stand a better chance of mitigating losses and safeguarding their incomes. The province’s extensive cashew acreage, which underpins the economic well-being of countless rural households, underscores the importance of collective vigilance. As climatic patterns exhibit increasing unpredictability, the ability of growers to respond swiftly to early warning signs of pest outbreaks or fungal activity will determine the resilience of this vital agricultural sector in the years ahead.

Continued collaboration between agricultural authorities and farming communities will prove essential in translating current challenges into opportunities for enhanced preparedness. By drawing directly on the insights gained from the recent weather events, stakeholders can refine management strategies to better protect the 175,000 hectares of cashew orchards and the tens of thousands of families who depend on them. In this manner, Dong Nai can maintain its position as the nation’s premier cashew region even as environmental conditions evolve, ensuring stable production levels and sustained contributions to Vietnam’s agricultural economy for seasons to come. The experiences of recent days serve as a clear reminder that timely, science-based responses remain the most effective defense against the threats posed by unusual weather to one of the province’s most valuable crops.