is a Plant Pathologist and President of Chase Research Gardens, Inc.
C.R.G. is a private research and consulting corporation specializing in
Both hourly and contract services are available.
You can reach C.R.G. at P.O. Box 168, Mt. Aukum, CA 95656 Phone and Fax:
916-620-1624 - E-mail: MTAUKUM@AOL.COM
mottle on Fittonia
Pathogen - Bidens Mottle Virus
Symptoms - Distortion of the normally symmetrical leaves
is the most common symptom of this viral disease. Yellowing between
veins and stunting can occur on severely infected plants. The disease
appears to be most severe during the cooler periods of the year.
This disease has rarely been seen on fittonias during the past ten
Control - This virus is transmitted from common weed hosts
to the fittonia via aphid vectors. Remove weeds from around greenhouses
as much as possible and keep aphid populations under control. Once
plants are infected they should be removed and destroyed since they
will not recover from the infection even if they don't show symptoms
on a continuous basis.
injury on Fittonia
Pathogen - Air temperatures below 45° or 50°F
Symptoms - Youngest leaves are most sensitive to chilling
injury and develop white to tan splotches, especially near leaf
edges. Exposure to 50°F will cause leaf burning but will not result
in wilt and tip damage. Leaf wilt and flower collapse occur if nerve
plants are exposed to temperatures below 45°F for extended periods
Control - Keep production air temperatures at least 55°F.
The damage is permanent, but plants will produce healthy leaves
when air temperatures are adequate, unless the shoot tip has been
damaged by extreme cold for extended periods.
of Pilea cadierei
Pathogen - Cool air temperatures with excess soil moisture
Symptoms - Leaves develop a warty appearance, especially
near edges. These raised areas are easiest to see on undersides
of leaves and may be slightly water-soaked or tan.
Control - Be careful to control the amount of water supplied
to plants when the air temperatures are unseasonably cool.
Pathogen - Rhizoctonia solani
Symptoms - Discrete spots form all over plant foliage. The
web-like mycelium of the fungus is usually reddish-brown or tan
and can cover any part of the plant. Infected leaves wilt and die
Control - Cultural controls for Rhizoctonia aerial blight
are the same as for any soil-borne fungus. Do not reuse pots without
thorough cleaning and never reuse soil from infected plants that
have died. Grow plants away from the ground and avoid overwatering,
which stresses the plant and allows the pathogen to attack more
easily. Chemical control of this disease can be achieved with applications
of thiophanate methyl (Cleary 3336, Domain and others) which are
labelled for ornamental crops. Be sure to check labels for legal
use rates and intervals prior to application.
leaf spots on Fittonia, Pilea and Pellionia
Pathogen - Xanthomonas campestris
Symptoms - Symptoms on aluminum plant (Pilea cadierei) are
dry, tan, irregularly shaped spots found primarily in the white
areas of the leaves. Spots on other pileas tend to be dark brown
to black and may be angular in shape since they rarely spread across
leaf veins. Symptoms on pellionias are dryish, irregularly shaped
spots with a corky, slightly raised border found mainly on leaf
undersides. Hosts include aluminum plant, creeping Charley, Pilea
spruceana, Pilea invulcrata (silver tree), satin pellionia, and
trailing watermelon begonia. Creeping Charley and satin pellionia
were most susceptible, while trailing watermelon begonia was relatively
Fittonias are commonly infected with a similar but distinct bacterium
which cannot infect pileas or pellionias. Most producers do not
recognize the symptoms as a disease problem since edge burning and
vein blackening are the most common symptoms. These are sometimes
confused with irrigation, phytotoxicity, or temperature problems.
All types of fittonias have been found to be susceptible to this
pathogen, as were some related plants such as Aphelandra squarrosa
Control - Chemical control of both bacterial diseases is
rarely successful and cultural methods should be the first line
of defense. Fittonias are especially sensitive to streptomycin sulfate
and copper compounds; disease severity actually increases when these
compounds are used on fittonias infected with Xanthomonas sp. Elimination
of overhead watering and/or exposure to rainfall aid in control
of disease development and spread. However, once infection occurs,
lesions can expand even when leaves are kept dry. Discard all plants
infected with this pathogen and never use infected plants for stock,
since the disease is easily carried on tissue even though no symptoms
are evident. Unfortunately, plants with the highest quality were
found most susceptible to this disease in fertilizer trials. Other
plants susceptible to the Xanthomonas sp. from Pilea and Pellionia
spp. include many Ficus spp. and bird-of-paradise (Strelitzia).