Pest and disease prevention on off-shore vegetative cuttings

On a commercial scale, herbaceous ornamental plants are primarily propagated by three methods: seeds, vegetative cuttings, and tissue culture. The majority of vegetative cuttings for the U.S. market are harvested from stock (mother) plants located in Mexico, Central and South America, and Africa as they have subtropical-to-tropical climates that typically do not require utilities for heating and cooling and are at elevations of 1,600 to 5,000 feet (500 to 1600 m). Additional considerations include: worker wages, good transportation infrastructure, airports with refrigerated cooling facilities and regular direct flights to important export markets and politically stable government.

Generally, stock plant production consists of several sequential phases that require strict sanitation protocols, water management, scouting, and testing established by the operations themselves, often exceeding those of the USDA-APHIS Plant Protection and Quarantine (PPQ).

This all begins with a “clean” stock program that rigorously follows protocols to prevent the introduction and spread of harmful fungal, bacterial, viral, and viroid pathogens. Cuttings that successfully complete the clean stock program are used to establish a small population of elite nucleus or nucleus stock plants, which serve as the source material for the next generation of plants known as the increase block. Cuttings harvested from the increase block are then used to establish the third and final generation of stock plants in the “general production” area, where commercial cuttings are produced for harvest and shipment.