| Disease |
Symptoms |
Pathogen/Cause |
Management |
| Boron Deficiency |
Small, dark-brown to black irregularly shaped
spots form at the leaf base of seedlings. Plants wilt and die
as the browning spreads up the leaf blade. On older plants,
flower stalks are short and wilted. Plants die. |
Lack of boron |
Apply boron. |
| Botrytis Blight |
Small, water-soaked lesions form on damaged petioles
and spread to leaf blades. Infected flowers fade prematurely. |
Botrytis cinerea |
Space plants and provide ventilation to avoid
high humidity. Remove fading flowers and yellowing leaves. Apply
chlorothalonil or iprodione to protect healthy tissue. |
| Foliar Nematode |
Small, tan, sunken areas form on leaf tips and
margins. Spots become dry and dull black. |
Aphelenchoides ritzema-bosi |
Destroy infected plants. Water plants in a manner
that keeps leaf surfaces dry and does not splash from plant
to plant. |
| Myrothecium Rot |
Petioles of lower leaves develop darkened spots.
Spots enlarge down stems and stems are easily broken. |
Myrothecium roridum |
Plant in pasteurized media. Apply iprodione to
leaves and stems. Maintain moderate temps. and low humidity. |
| Phytophthora Crown Rot |
Crowns and roots have a dark, water-soaked appearance.
This spreads to petioles and leaf blades. Young plants are quickly
killed. Rhizomes of mature plants resprout but eventually succumb. |
Phytophthora nicotianae
var. parasitica, P.
nicotianae var. nicotianae,
P. cryptogea |
Do not propagate from infected plants. Pot in
pasteurized media. Destroy infected plants Apply etridiazole,
propamocarb, etridiazole + thiophanate methyl, mefenoxam, or
metalaxyl to protect healthy plants. |
| Pythium Root Rot |
Roots are dark brown. Plants wilt, yellow, and
die. |
Pythium |
Pot in pasteurized media. Destroy infected plants
Apply etridiazole, propamocarb, etridiazole + thiophanate methyl,
or metalaxyl to protect healthy plants. |
| Viruses |
Leaves have dark-brown to black dead areas in
line patterns. Flower petals are spotted. Leaves may be downwardly
cupped, mottled, or narrowly shaped. Leaves may have line or
ringspot patterns. Shoots may be elongated. |
Impatiens necrotic spot virus, tobacco mosaic,
or tomato ringspot virus |
Maintain good thrips control including screen
them out with fine-mesh screen. Destroy infected plants. Eliminate
weeds within the production area. Do not use tobacco products
when handling plants. Keep gloxinias away from cineraria, holiday
cactus, cyclamens, and other crops known to be very susceptible
to impatiens necrotic spot virus. |
