Phytophthora Fruit Rot Control: How to Identify and Get Rid of Phytophthora Fruit Rots

Phytophthora fruit rot is a fungal disease with a wide range of hosts, most of which are those with fruits that are close to the soil. Aside from the presence of the fungus causing the disease, the problem can exacerbate if the environmental conditions are favorable. Luckily, there are easy and practical control measures that can be effective in getting rid of this disease.

What is Phytophthora Fruit Rot?

This is a plant disease caused by the Phytophthora citricola fungus, which is also the one responsible for collar rot, seedling damping-off, stem lesions, leaf spots, and foliar blight, among others. This plant pathogen was first introduced in Taiwan in 1927. It is common in fruits that hang low on the ground or those that are already touching the soil. In most cases, damage happens if the fruit is about 3 feet from the ground.

The fungus exists in the form of a water mold that lives in the soil. Water is one of the factors that are essential for the transfer of spores to the other plants. The wind will also contribute to the spread of the spores. They can infect the plant directly or through its open wounds, often caused by insects and other garden pests. Machinery that has been in contact with a plant suffering from an infection can also carry the fungus.

It favors environments that are wet, moist, or humid. They will grow at a minimum temperature of 3 degrees Celsius and maximum temperature of 31 degrees Celsius. The ideal temperature for their growth, on the other hand, ranges from 25 to 29 degrees Celsius.

Phytophthora Fruit Rot

Phytophthora Fruit Rot on Watermelon

Identifying Phytophthora Fruit Rot’s Damage

Host Plants

This disease can affect a wide array of plants, with some of the most common hosts being winter squash, pumpkin, eggplant, watermelon, pepper, strawberry, guava, avocado, tomato, fig, onion, and citrus.


The following are some of the most common symptoms of phytophthora fruit rot:

  • The first sign of the disease would be water-soaked spots on the fruit. This will appear on the underside as this is the part of the fruit that is touching the ground.
  • When the fungus spreads, especially when the fruit becomes wet from rain or irrigation, the spots will be apparent even on the upper part.
  • Aside from depressed spots, white and yeast-like structures will also appear on the fruit. This covering, however, does not usually grow thick.

Results of Infestation

The fruit suffering from the disease will show cosmetic damages. Its outer appearance will be unattractive. In the initial stages, the damage will be small, but as the disease progresses, it will be more noticeable. For commercial growers, this means that they will have a hard time selling their product because of their unattractive appearance. In the latter stage of the infection, the fruit will turn soft and will rot. It can lead to economic losses.

Phytophthora Fruit Rot

The Fruit Suffering from the Disease Shows Cosmetic Damages

How to Get Rid of Phytophthora Fruit Rots

Natural and Organic Solutions

To prevent this disease from causing significant damages to your plants, the following are some of the best things to do:

  • Plant crops that will resist the pathogens carrying fruit rot. In relation to this, you should also practice crop rotation. Avoid planting the same crops for two consecutive seasons. As much as possible, alternate the previous crop with one that is resistant for the next growing season.
  • The right watering techniques and proper irrigation will also be crucial in the prevention of Phytophthora fruit rot. Rainfall and irrigation can cause too much moisture in the soil, making it more attractive for pathogens. With this, utilize drip irrigation and water early in the morning, which will provide you with the assurance that it will dry out.
  • Elevating the fruit will also be a good solution. Raising it from the soil or having a protective barrier between the soil and the fruit will help to inhibit the transfer of the fungus.
  • You also need to be cautious about the equipment or tools that you are using. Even shears or scissors can be carriers of pathogens. With this, be sure to sanitize your tools so that it will not cause the disease to spread.
  • A thick layer of mulch will also help. Like a cover on the soil, this will act as the barrier to prevent the pathogens from getting close to the fruit.
  • Remove any fruit that you can find on the ground, especially if it is already rotting. If you leave it, the spores can transfer to the healthy fruits and the infestation will spread.

Chemical Solutions

There are no chemical treatments that are effective in getting rid of Phytophthora fruit rot when the symptoms are already apparent. For the best way to deal with the disease, use a combination of the methods that we have mentioned above.

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