Developing sustainable pest management strategies against major pests of papaya in Hawaii

Developing sustainable pest management strategies against major pests of papaya in Hawaii

Summary

Hawaii is the biggest papaya producing state in the country, exporting most to the mainland U.S. continent. This project aims at developing sustainable pest management techniques against major papaya pests: white peach scale, thrips, mites, papaya mealybug and nematodes. Kaolin clay and horticultural oil are tested for insect and mite control, and sunn hemp is tested for nematode and thrips control. An economic analysis will provide insights in the viability of the proposed pest management practices. Results of the project will be disseminated to stakeholders and other interested parties throughout the duration of the project.

Objectives/Performance Targets

1. Examine the effectiveness of organic pesticides kaolin clay, petroleum oil and their combination against papaya insect pests.

2. Examine the benefits of sunn hemp living mulch as a trap crop for Thrips parvispinus.

3. Demonstrate the benefits of strip-till sunn hemp living mulch for nematode and soil health management in a papaya orchard.

4. Disseminate research findings to papaya growers and agricultural professionals.

5. Develop economic analysis of sustainable strategies for emerging pests of papaya in Hawaii

Accomplishments/Milestones

Two field trials were done during 2013; one on the Island of Oahu and another one on Hawaii Island. Given the results of kaolin clay in our 2012 trials, this treatment was dropped and BotaniGard was added. BotaniGard is a botanical insecticide based on the entomathogenic fungus Beauveria bassiana. BotaniGard controls a wide variety of soft-bodied insects such as whiteflies, thrips, aphids and mealybugs. BotaniGard has a unique formulation, having the highest spore concentration in a Beauveria-containing insecticide.The field trials ran from December 2012 to September 2013. Results from the two trials are summarized below:

• The oil treatment had lower mean numbers of thrips per flower on both Oahu and Big Island trials (Fig 1. A & B)

• On the Big Island trial, standard practice did the best controlling scale populations in trunks (Fig. 2).

• Mixed results in 2013. Big Island oil treatment had the lowest yield (due to high scale infestation that reached the fruit). Standard practice was the best treatment in 2013 for the Big Island study, followed by Botanigard. (Fig. 3)

• Oahu oil treatment was superior than the standard practice. Oahu trial had significantly less unmarketable fruit (fruit with insects or insect damage) than the Big Island trial. (Fig. 3)

• Timing of the start of preventive treatment seems to be the key to prevent pest build up. Plants in the 2013 study on Big Island were older than plants in 2012 study. Oahu plants were of similar age as the Big Island 2012 study, and therefore were more protected against pest invasion during the study period.

• Efforts were made to plant sunn hemp to test the effect on soil health and the effect on plant parasitic nematodes, but, unfortunately, the field on Big Island had very poor germination rates and the field on Oahu was turned in but left fallow for several months before planting. We will try again in spring 2014.

The PI presented results from the first and second year trials at the annual grower’s conference of the Hawaii Papaya Industry Association and at the 2013 Sustainable and Organic Agriculture Program’s Extension and Research Update. Cost-benefit analyses are still pending for the 2013 trials.

• scale data

Impacts and Contributions/Outcomes

Results from the second year trials showed that the oil treatment did not work well in papaya plantations that are older. For better protection of the plants, oil treatments might need to be started early as a preventive measure to avoid pest builups, and or the use of toxic insecticides.

• Flower data
• yield data

Collaborators: