| Disease |
Symptoms |
Pathogen/Cause |
Management |
| Alternaria Leaf Spot |
Dark-brown to black spots form on
leaves. These enlarge to engulf large portions of the leaf.
Spots on petioles may allow them to break. |
Alternaria
sensecionis |
Remove infected leaves. Water in
a manner that keeps leaf surfaces dry. Maintain low humidity.
Apply iprodione or mancozeb to protect healthy plants. |
| Downy Mildew |
Yellow spots on leaves become black.
Sparse fungal growth may appear on the underside of infected
leaves. |
Plasmopara
halstedii |
Water in a manner that keeps leaf
surfaces dry. Remove infected leaves. Apply mancozeb to protect
healthy plants. |
| Phytophthora Root and Collar rot |
Roots and stem at the soil line rot.
Plants wilt and die. |
Phytophthora
cinnamomi, P. cryptogea,
P. megasperma, and P. drechsleri |
Plant in pasteurized potting mix.
Apply etridiazole to protect healthy plants. |
| Powdery Mildew |
White fungal growth forms on the
leaf surface. |
Erysiphe
cichoracearum or Sphaerotheca
fusca |
Heat and ventilate to maintain low
humidity at night. Apply Ampelomyces
or triadimefon to protect healthy plants. |
| Viruses |
Leaves may be mottled, have yellow
spotting, dead flecks, line or ring spot patterns. Plant may
be distorted, have flower color breaking, or may be stunted.
Veins may be killed along with petioles and the entire plant. |
Tomato spotted wilt, impatiens necrotic
spot, streak and mosaic viruses |
Destroy infected plants. Maintain
good insect and mite control. |
