Gourd Pests and Diseases
Bacterial Wilt of Cucurbits
Cucurbit Disease Management (including fungicides)
Powdery Mildew of Cucurbits 1
Powdery Mildew of Cucurbits 2
Powdery Mildew on Ornamentals
Controling Powder Post Beetles
Cornell Cucurbit Factsheets
2000 Guidelines for managing powdery mildew and other diseases of cucurbits
Classes of Fungicides: Inorganics are protective (preventative) fungicides
Sulfur: one of oldest fungicides used, about 8 million pounds used in 1990 in U. S.; works as a general growth inhibitor; advantages include cheap cost and ease of application (dusts); disadvantages include limited spectrum of activity (best on mildews), must be applied frequently at a high rate and phytotoxic at high temperatures.
Classes of Fungicides: Copper
Copper: phytotoxic to plants in elemental form (use uncommon) . Copper is bound to organic and inorganic molecules in fixed-type coppers, less toxic to plants. Broad spectrum poison; useful as fungicides and bactericides; protective (preventative) fungicides: Bordeaux mixture (copper sulfate and hydrated lime), copper sulfate, copper hydroxide and other copper compounds.
Classes of Fungicides: Organics
Organics are protective (preventative) fungicides: Broad spectrum control, multi-site activity represent 60-70% of fungicides used. Dithiocarbamates: thiram; Ethylenebisdithiocarbamates (EBDCs): manozeb, maneb and zineb; Captan: one of the most widely used fungicides worldwide, broad spectrum control; Chlorothalonil (Bravo, Daconil 2787): widely used, ornamentals and turf.
Classes of Fungicides: Systemics
Systemic and/or curative activities; Benomyl (Benlate): broad spectrum, widely used; Thiophanate-methyl (Topsin-M): broad spectrum, turf and fruit; Iprodione (Chipco 26019, Rovral): broad spectrum, turf and ornamentals; Metalaxyl: seed treatments (Apron), field and vegetable crops (Ridomil), and turf and ornamentals (Subdue); narrow spectrum of activity, effective against certain soil-borne diseases.
Classes of Fungicides: Sterol inhibitors
Sterol inhibitors: large group of fungicides, widely used, broad spectrum of activity, has both protective and curative activity; include imazalil (Fungaflor), triforine (Funginex), fenarimol (Rubigan), mycobutanil (Nova), propiconazole (Tilt) and triadimefon (Bayleton).
Classes of Fungicides: Fumigants
Highly volatile chemicals that have fungicidal activity; include methyl bromide (controls fungi, nematodes, insects and weeds) and chloropicrin.
Classes of Fungicides: Antibiotics
Antibiotics are substances produced by microorganisms which inhibit growth of plant diseases in very dilute concentrations. Streptomycin (Agri-Mycin): used as dust, spray and seed treatment, mostly for bacterial diseases.
Proper Timing of Application to Spray Nova or Bayleton for Control for Powdery Mildew
For most diseases it takes at least a week from the time the fungus enters the plant until the symptoms appear. In the case of Phomopsis fruit rot, the fungus enters the fruit during bloom and symptoms do not appear until the fruit begins to ripen (harvest). Depending upon the weather, it may take two weeks for black rot symptoms to appear. Once symptoms appear, it is too late to control the disease; therefore, proper timing of the application is critical. The fungus must be controlled before or shortly after it enters the plant.