People living in the Los Angeles, California Basin have known for years that smog
affects plants. There exists a similar situation
on the Big Island of Hawaii. It’s called VOG, emissions that spew from the Kilauea Volcano at Halemaumau. The discharges include sulfur dioxide,
sulfites, ash and hydrochloric acid.
Many gardeners, especially those
living near the Volcano area, have experienced the distressing effects of vog on
their plants. Sulfur dioxide enters the leaf through the stomata. The degree of injury will depend upon its
concentration and duration, and upon the sensitivity of the specific plant. The
symptoms of low concentrations of sulfur dioxide are general chlorosis
(yellowing) of the plant foliage. Higher concentrations cause a bleaching or
browning of tissues between the leaf veins.
Volcanic ash appears as a dust and is composed of fine rock particles
from the volcano. The ash does not damage plants directly but can block
sunlight on foliage as well as detract from the appearance of the plant.
Harvested fruits and vegetables should be thoroughly washed prior to their
consumption.
There is not much that can be done about the harmful chemicals the volcano
churns out. As far as the plant is concerned however, leaves should be rinsed with adequate water
after exposure. Susceptible plants can be grown under cover such as greenhouses, and during periods of intense vog, valuable plants can be temporarily covered
with fabric or plastic.
Different plants have varying degrees of susceptibility to vog. Here is a list of plants documented to be
susceptible to vog:
Ornamentals - African
lily, Oriental lily, cypress, Dutch iris, eucalyptus, ginger, hydrangea,
heavenly bamboo, pine, podocarpus, rose and tuberose.
Native
plants - koa, naio, pilo, uki, akala.
Vegetables
- broccoli, cauliflower, Chinese cabbage, daikon, lettuce, Swiss chard,
tomato and watercress.
Some of the more resistant plants are asparagus, celery, coffee,
corn, and ohia.
For a more in depth look at the volcano’s effects on plants, with some excellent
photographs, read, “Volcanic Emissions Injury to Plant Foliage”, by Scot Nelson
and Kelvin Sewake, UH Department of Plant and Environmental Protection
Sciences. The publication can be found on the CTAHR website -
http://www.ctahr.hawaii.edu/Site/Info.aspx
