Disease Control
Damping-Off.
Apply the following in a 7-inch band after seeding. Use formula in the "Calibration for Changing from Broadcast to Band Application" section of Calibrating Granular Application Equipment to determine amount of Ridomil Gold or Ultra Flourish needed per acre.
mefenoxam -- l-2 pt Ridomid Gold 4E/A or 2-4 pt Ultra Flourish 2E/A
Viruses (CMV, WMV, PRSV, ZYMV). Use resistant varieties where possible.
Plant fields as far away from existing cucurbit plantings as possible to prevent aphid transmission of viruses from existing fields to new fields.
Angular Leaf Spot/Bacterial Leaf Spot.
Both diseases can produce foliar symptoms that are often over-looked. Early detection is important, since control in the foliar phase can reduce infection of developing fruit. Both diseases are seedbome and can survive on infested debris for at least one year or until the debris decomposes. Apply the following when disease is first detected on the foliage and
repeat every 7 to 10 days.
copper, fixed -- 2-4 pt 2.4F/A or 1-2 pt 4.6F/A
Bacterial Wilt.
Insect control is essential for prevention of wilt. Control cucumber beetles before they feed on plants.
Powdery Mildew.
The fungus that causes powdery mildew has developed resistance to several classes of fungicides. The fungicides at risk for resistance development such as Strains of the pathogen that are highly resistant to some strobilurins/Class 11/QoI fungicides (Cabrio, Flint, Amistar, Quadris and Tanos) have been reported in the Eastern U.S. in 2004 and 2005.
Powdery Mildew generally occurs from mid-July until the end of the season. Excellent resistance is available in all recommended cucumber varieties. Observe fields for the presence of powdery mildew. If one lesion is found on the underside of 45 old leaves, begin the following fungicide program:
Alternate
Chlorothalonil (Bravo, Echo, Equus)--2-3pt 6F/A or OLF plus Nova--5oz 40W/A, or
Chlorothalonil (Bravo, Echo, Equus)--2-3pt 6F/A or OLF plus Procure--4-8 oz 50WS/A,
with
Micronized Wettable Sulfur 4 lb 80W/A, sulfur may injure plants especially at high temperatures. Certain varieties may be more sensitive. Consult label for precautions, or
Pristine 12.5-18.5 oz 38WS/A, or
Vydate L--1-2 gal 2L/A. Incorporate into the top 2 to4 inches of soil or 2 to 4 pints 2L per acre applied 2 weeks after planting and repeat 2 to 3 weeks later.
Downy Mildew.
The disease generally does not occur until mid-August, however, scout fields for disease incidence. Refer to the Cucurbit Downy Mildew Forecasting website (http://www.ces.ncsu.edu/depts/pp/cucurbit/) for current status of the disease. Begin sprays when vines run, or if disease occurrence is predicted for the region. Preventative applications are much more effective than applications made after disease is detected. Resistance to the QoI/Class II fungicides has been reported in the Eastern U.S. The following are the most effective materials (tank mix these products with a protectant such as chlorothalonil (Bravo, Echo, Equus)--1.5 pt 6F/A or OLF or maneb--2-3 pt 4F/A or OLF):
Ranman--2.1-2.75 fl oz 400SC/A or
Previcur Flex--1.2pt 6F/A or
Curzate--3.2 oz 60DF/A or
Pristine--12.5-18.5 oz 38WG/A, or
Tanos--8 oz 50 WDG/A or
Cabrio--8-12 oz. 20WG/A.
Materials with different modes of action (FRAC group) should be alternated.
Sprays should be applied on a 7-day schedule. Cabrio, Pristine and Tanos should not be alternated with each other or used consecutively. Under severe disease conditions spray interval may be reduced if label allows.
Plectosporium Blight (Microdochium).
Research studies have shown that no-till pumpkin production results in less disease. Rotate with crops other than cucurbits. It is important to achieve maximum foliage coverage with the fungicide application. Once symptoms appear on petioles or after fruit form, apply the following and repeat every 7 days:
chlorothalonil (Bravo, Echo, Equus)--1.5-2 pt 6F/A or OLF
maneb--2-3 pt 4F/A or OLF)
A spray schedule that alternates Cabrio or Flint with chlorothalonil will also provide control.
Scab.
Disease occurs during cool periods. Use resistant varieties when possible. Begin sprays as true leaves form. Repeat every 5 to 7 days.
chlorothalonil (Bravo, Echo, Equus) -- 2-3 pt 6F/A or OLF
Gummy Stem Blight(Black Rot) and Anthracnose.
Rotate to provide at least 2 years between cucurbit plantings. Pumpkin variety Small Sugar appears to be the least affected by Black Rot.
Fungicides at risk for resistance development such as strobilurins/Class 11/QoI fungicides (Cabrio, Flint, Amistar, and Quadris ) should be tank-mixed with a different class of fungicide to delay onset of resistance. When tank-mixing use at least the minimum labeled rate of each fungicide in the tank mix. Alternate with a non-QoI fungicide effective against gummy stem blight. Do not apply a QoI fungicide more than 4 times per season. If resistance to QoI fungicides exists in the area, do not use QoI fungicides. Use a fungicide from a different fungicide class.
Begin the following fungicide program when fruit start to form:
Alternate:
chlorothalonil (Bravo, Echo, Equus)--2 pt 6F/A, or
mancozeb( Dithane, Manex II, Manzate, Penncozeb)--2-3 lb 8OWP/A
with a tank mixture containing chlorothalonil and
Pristine--12.5-18.5 oz 38WG/A, or
azoxystrobin (Quadris--11.0 - 15.4 oz 2.08F/A or Amistar--3.5-5 oz 80WDG/A, or
Cabrio--12-16 oz 20EG/A, or
Maintain fungicide schedule until harvest. See the "Harvesting and Storage" section. Fungicide application for black rot control will help maintain "handles" on the fruit.
Harvest carefully because wounding can negate benefits from a season-long fungicide program.
Phytophthora Blight.
Rotate with crops other than peppers, eggplants, tomatoes, and other cucurbits. Fields should be adequately drained to ensure that soil water does not accumulate around the base of the plant. Broadcast soil fumigation 2 to 3 weeks prior to seeding is beneficial in areas that justify the expense.
For protection against the fruit rot phase of the disease, apply the following when conditions favor disease development:
Forum--6 oz 4.18SC/A, (must be tank mixed with another fungicide active against Phytophthora blight on pumpkins and winter squash such as fixed copper), or
Ranman--2.75 fl oz 400SC/A, or
Tanos--8 oz 50 WDG/A (suppression only)
Information provided is intended for consideration by the user, but is not intended to be a recommendation. Production decisions should be based on consideration of many types of information (scientific, experiential, economic, legal, etc.) available to the user.
Where trade names are used no discrimination is intended, and no endorsement by the Cooperative Extension Service is implied.
Dr. Alan A. MacNab, Professor, Plant Pathology
Penn State College of Agricultural Sciences
211 Buckhout Lab, University Park, PA 16802
Updated: Nov, 2005; EMH
Loaded: Nov, 2005; EMH