- OOMYCETE DISEASES OF CUCURBITS 281
C.Pythium Diseases
1 .Symptoms
2 .Pathogen Biology
3 .Host Range
4 .Disease Cycle and Epidemiology
5 .Disease Management
IV.CONCLUDING REMARKS
Literature Cited
I. INTRODUCTION
The Cucurbitaceae, also known as the gourd family, consists of 98 gen-
era with over 975 species (Anon. 2015). Some of the important gen-
erainthisfamilyareCitrullus,Cucurbita,Cucumis,andLuffa(Janick
and Paull 2008). Commonly grown cucurbits are cucumbers (Cucumis
sativus), gourds (Cucurbita pepoandC. maxima), melons (Cucumis
melo), pumpkins (Cucurbita pepoandC. moschata), summer squash
(Cucurbita pepo) and winter squash (Cucurbita maxima), and water-
melon (Citrullus lanatus). Cucumbers are grown for fresh market and
pickling. Gourds are edible and ornamental. Ornamental gourds are col-
orful and vary in size and shape. Melons include cantaloupe, honeydew,
muskmelon, netted melon, and casaba. Pumpkins, commonly known as
jack-o-lanterns and processing pumpkins, are grown for food, feed, and
ornamentals. The squash group includes yellow squash, zucchini, and
various winter squash varieties.
Cucurbitaceae ranks among the highest of plant families for number
and percentage of species used as human food. Cucurbits are major veg-
etables grown worldwide, mainly in the tropics and temperate areas.
These crops are grown in both indoor (glasshouses and plastic houses)
and open fields (gardens and commercial fields). Cucurbits can be
directly seeded and transplanted. They are sensitive to frost and ger-
minate and grow poorly in cool, wet soils (Zitter et al. 1996). Except for
watermelons, all of the cucurbits mentioned above grow best in soils
with a pH of 6–7; watermelons grow well in soils with a pH of 5.5–6.8.
Cucurbits grow well in soils with high levels of organic matter.
There are more than 200 known biotic (infectious) and abiotic (nonin-
fectious) diseases of cucurbits (Zitter et al. 1996; Babadoost et al. 2004).
Infectious diseases are caused by bacteria and mollicutes, oomycetes,
fungi, viruses and viroids, nematodes, and parasitic plants. Most cucur-
bit diseases are caused by fungi, as is the case for all plant diseases.
Noninfectious diseases (disorders) are caused by a multitude of con-
ditions, including extremes in temperature, light, soil pH, nutritional