California and Arizona citrus nursery growers are shifting production of critical plants from the outdoors to ‘indoor protective structures’ to gain protection from the Asian citrus psyllid (ACP) insect and its primary vectored disease Huanglongbing (HLB).

ACP and HLB are major threats to the U.S. citrus industry. The ACP was first found in California in August 2008 and in Arizona in October 2009. Neither state has HLB, a disease which kills every tree it infects.

Growing plants indoors is much different than outdoor production, says Jim Bethke, University of California Cooperative Extension floriculture farm advisor in San Diego County.

“The plants change, the pests change, and the soil and growing environment changes.”

Bethke has spent decades helping San Diego County ornamental plant growers successfully farm plants in greenhouses. He shared his experiences and what citrus nursery growers could experience in indoor production during the “Life on the Inside” citrus nursery workshop in Ontario, Calif., in mid August, sponsored by the California Citrus Nursery Board.

One of the first realities of growing plants indoors is the pest complex can increase.

“You’ll likely find extra pests indoors that you haven’t dealt with outside including mites and thrips,” Bethke told the citrus nursery crowd. “It’s very hard to exclude mites with screening material. The screen can exclude the Asian citrus psyllid, but will not keep out thrips.”

For decades, pesticide applications in greenhouses have typically followed a calendar schedule. Ornamental plant growers are keenly aware that mites and aphids show up in the spring and leafminers appear closer to summer. Pesticides were applied whether the pest was present or not.

The more recent trend in greenhouse production is reduced pesticide use due to integrated pest management (IPM) strategies plus effective pest monitoring and scouting.

“A lot of time and effort is spent looking for pests and positively identifying the pests,” Bethke said. “Every effort is made to control pests before pesticides are ever applied.”

A knowledgeable staff is critical to this success and in a small operation staffing may include strictly the owner.

In larger operations with multiple employees, Bethke recommends a three-member team – one member each to focus on IPM, decision making, and plant production. The team should meet on a regular basis.

“The IPM team should closely monitor plants for pests and then record and summarize the information on paper,” Bethke said.

The scout monitors for pests and the decision maker decides if the pest has reached a level that requires a control measure. The grower, the most familiar with the crop, walks the crop on a daily basis and can identify problems with the plants. These three working together can make good decisions on needed pest control.