rain season

How to ensure crop protection and correct pesticide application during rain season?

Climatic conditions are part of the main elements that affect the success of a crop. That is, factors such as temperature and humidity have a direct impact on plant growth.

These conditions also have an influence on the efficiency of some operational processes, such as pulverization. A rain season, for instance, may reduce or even interrupt the effect of pesticides, generating a significant losses for farmers.

Unfortunately, farmers are unable to control the climate. But they can prepare their plantations to prevent and reduce the damages related to typical weather conditions of the rain season.

In this article, you’ll get to know which methods have been used to protect plantations during the rain season. You’ll also understand how to apply pesticides with efficiency even in rough climate conditions.

How to protect your plantation during rain season?

There are several methods that you can employ to protect your crops during the rainy season. Here, we will consider the most practised methods today.

Monitor atmospheric conditions

There is no way to make an exact forecast. However, a good monitoring of the atmospheric trends may reveal predictions that must be considered when taking measures to protect production. And it is not only a matter of presence or absence of rain: the regularity and distribution of precipitations are also important.

The data provided by satellites are essential for this purpose. Farmers can have access to this information through several tools that allow the monitoring of crops and their relation with climate, as well as indicators of losses or anomalies in harvest.

Several initiatives are making data more accessible to farmers. In Southern Africa, a new satellite had been introduced by NASA Harvest, which is NASA’s Food Security and Agriculture Programme in partnership with the Food and Agriculture Organization of the United Nations (FAO).

The project aims to enhance monitoring of crops, combining satellite technology and a specific training to help regional agencies and FAO local offices with the use of Earth Observations Indicators.

Plan harvest periods carefully

Nowadays, it is possible to forecast meteorological condition well in advance. Even if forecasting does not provide exact data, we can still acquire accurate information about temperature and level of precipitation, among other relevant factors. With this, farmers are able to plan their strategies adequately, and anticipate or postpone planting and harvesting of selected cultures.

This meteorological data is also useful to chose specific cultures according to the length of their cycle: shorter or longer. For example, when a drought period is forecasted, you may choose varieties of corn or soy with different cycles. Another option is to delay sowing to protect crops from adverse weather conditions.

Use technology that provides climate alerts

In the market there are several platforms providing the technology able to send alerts when the climate changes, or when environmental extremes and other risks may arise. Make use of these solutions in order to guarantee you can get critical information in time to take the necessary actions.

Manage machine traffic

Vehicles are key in every stage of the productive cycle, but they need to be used properly to prevent any damage to the crop. Thus, during rainy season, the days when machines will be running must be chosen carefully. For instance, if your vehicles move over wet terrain, they can compact the soil, which may cause a loss of macronutrients.

Then, in case it is really necessary to use machines on rainy days, the best attitude is to accurately plan the traffic, defining a fixed path to reduce the impacted area.

How to apply pesticides according to climate variables?

There are four primary variables to observe, as presented below.


Spraying pesticides when it rains is a complete waste. Pesticides usually need some time to be absorbed by plants to produce the expected effect. So, with precipitations, you don’t get satisfactory protection.

And considering that plants need time to properly absorb the spray, it’s important to point out that you also need a reliable forecast about rains for the period that follows application. An unexpected rain after spraying pesticide may remove the product and mess up your work, making it necessary to proceed with a new application.

The time necessary between product application and a condition of rain vary according to the pesticide that is used. Therefore, it is important to take into account the orientations provided by the supplier. Some products require a minimum of two hours without rain.

It is also important to double-check if crops are dry after a rainfall before applying products. For this, a good technique is to shake some plants: if there is still water splashing, it’s better to wait awhile.

Air humidity

This is one of the most important variables to analyse before pesticide application. The rule stands that the lower the humidity is, the faster the pesticide droplets will lose humidity before they hit their target. And if the humidity gets too low, these droplets may not reach the plants due to loss of mass and strength. Then, the ideal situation is an air humidity between 55% and 95%.


High temperatures must be avoided because they accelerate evaporation, generating an ascendant airflow that slows the droplets’ fall. Because of this, applications are recommended when temperatures are not exceeding 32ºC.

On cold days (below 15ºC), some products may not work properly, so it is necessary to check recommendations for each pesticide. In addition, low temperatures decelerate the plants’ metabolism, which reduces their product absorption capacity.


Strong winds can result in drift and affect the droplet’s trajectory, deflecting it from the target. A low incidence of wind (between 0 and 2km/h) is not an ideal condition because the hot air remains close to the ground, trapped by a layer of cold air. As a consequence, the spray particles end up in suspension, causing a loss of product. Then, the ideal wind speed during pesticide application is between 2 and 10 km/h.

For sure, accurate planning and adequate methods and technologies allow you to get good results from your harvests, even during rain season. New farming machinery also contributes to an enhanced South African agribusiness with an important place in the world.

Are you interested in gathering more information about the relation between climate and agriculture? Learn more about agrometeorology.


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