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  • 1. Introduction to Phytosanitary Treatments
  • 2. Types of Phytosanitary Treatments
  • 3. Barumba Berry Case Study
  • 4. Module Conclusion
• Topics
  • 1. Chemical Phytosanitary Treatments
  • 2. Non-chemical Phytosanitary Treatments
  • 3. Efficacy of a Treatment
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Lesson 2: Types of Phytosanitary Treatments

Topic 3: Efficacy of a Treatment

The target level of pest control for a treatment is known as the efficacy of the treatment. Chemical and non-chemical treatments are often used on their own, without other measures, to achieve a target level of pest control.

Generally, the efficacy of a chemical or non-chemical treatment is measured in terms of pest mortality. For example, the target organisms are killed. Many chemical and non-chemical treatments attempt to achieve Probit 9 mortality as the desired level of control. Probit 9 means that the treatment results in 99.9968% mortality of the target population or that for every 100,000 individuals treated there are only three survivors. Probit 9 is not a relevant measure of efficacy for irradiation because the goal of irradiation is not necessarily pest mortality. Properly irradiated shipments may arrive with “wrigglers.” “Wrigglers” are living insects that have been rendered non-viable or non-fertile by the treatment.

Treatment Schedules

Treatment schedules list combinations of dosage, exposure time, and temperatures of a given treatment that achieves the desired level of pest mortality for a specific pest and commodity. Treatment schedules are based on extensive research to determine which combinations of dosage and temperature or time and temperature will result in the desired level of pest control for each pest and commodity. The efficacy of a treatment is often achieved by different combinations of dosage and temperature for chemical treatments or time and temperature for non-chemical treatments. Treatment schedules are often provided by the governing agency that oversees plant protection for a given country. The International Plant Protection Convention has published International Standard for Phytosanitary Measures 28 (ISPM 28) and corresponding annexes to provide guidelines on treatments for regulated pests and specific treatments, such as irradiation, cold treatments, and heat treatments for specific pests.

Check with the governing agency in your country that oversees plant protection to see if they have developed their own treatment manual. Otherwise, ISPM 28 and the USDA Treatment Manual are good resources to create your own treatment manual.

Example Treatment Schedule for Chemical Treatments

Methyl bromide fumigation is a commonly used chemical treatment. Generally, methyl bromide fumigations at lower temperatures require a higher dosage of methyl bromide. This is due to lower temperatures results in lower respiration or breathing rates of the organism, which tends to make the fumigant less effective in killing pests. The relationship between methyl bromide dosage rate and temperature is shown in the treatment schedule for mealybugs on lychee below.

In the treatment schedule below, 4 lbs of methyl bromide at 60°F has the same efficacy in killing mealybugs as 2.5 lbs of methyl bromide at 80°F. In other words, the higher the temperature, the lower the required chemical dose; while the lower the temperature, the higher the required chemical dose.

Example Treatment Schedule for a Non-Chemical Treatments

Cold treatment is used to treat for fruit flies on a variety of different fruits. Generally, lower temperatures require shorter treatment times, while higher temperatures require longer treatment times to achieve the same level of efficacy. The relationship between temperature and exposure time is shown in the treatment schedule for Mediterranean and Natal fruit flies on a variety of fruits below.

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