Disease Control
Damping-Off. Apply the following in a 7-inch band after seeding. Use formula given in the "Calibration for Changing from Broadcast to Band Application" section ofCalibrating Granular Application Equipment to determine amount of Ridomil Gold or Ultra Flourish needed per acre.
mefenoxam--l-2 pt Ridomil Gold 4E/A or 2-4 pt Ultra Flourish 2E/A
Viruses (CMV, WMV, PRSV, and ZYMV).
Plant fields as far away from existing cucurbit plantings as possible to prevent aphid transmission of viruses from existing fields to new fields.
Bacterial Wilt.
Insect control is essential for prevention of wilt. Control cucumber beetles before they feed on plants. Early in the season when soil applications of Furadan are used for transplants, there may be insufficient uptake; therefore, foliar insecticide applications may have to be used.
Fusarium Wilt.
Rotate to allow 5 years between muskmelon plantings. Use resistant varieties when possible. Athena has resistance to Race 0, 1, and 2 (predominant races present in the area). Eclipse and Superstar have resistance to Race 2 only.
Phytophthora Fruit Rot.
To minimize the occurrence of this disease, rotate away from susceptible crops (Cucurbits, Peppers, Eggplants, and Tomatoes) for as many years as possible. Fields should be adequately drained to ensure that soil water does not accumulate around plants. Apply the following when conditions are favorable for disease development and always tank mix with another fungicide regestered on cucumbers.
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
Gavel--1.5-2 lb75DF/A
Tanos--8 oz 50 WDG/A (suppression only), or
Ranman--2.75 fl oz 400SC/A
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 containing chlorothalonil (above rates) plus
Pristine--12.5-18.5 oz 38WG/A
Downy Mildew
Use resistant varieties when possible. The disease generally does not occur until mid-August. However, scout fields for disease incedence beginning in mid-July. 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 occurence is predicted for the region. Preventative applications are much more effective than applications made after disease is detected. The following are the most effective materials:
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
Gavel 1.5-2 lb 75DF/A (Muskmellon varieties, 'Harvest Queen', 'Gold Star', 'Super Star', 'Sweet and Early', and 'Saticoy' are sensitive to Gavel). Gavel contains mancozeb, which is a protectant, and does not need a tank mix partner.
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.
Alternaria Leaf Blight.
Rotate muskmelons with unrelated crops. Begin sprays when vines begin to run, or earlier if symptoms are detected.
Alternate
chlorothalonil (Bravo, Echo, Equus)--2-3pt 6F/A or
mancozeb (Dithane, Manex II, Manzate, Penncozeb)--2-3 lb 75WP/A,
with
Pristine 12.5-18.5 oz 38WS/A, or
a tank mix containing chlorothalonil and:
azoxystrobin (Quadris--11.0 - 15.4 oz 2.08F/A or Amistar--3.5-5 oz 80WDG/A) (Do not use near apples, see label for details.), or
Cabrio--12-16 oz. 20EG/A, or
Reason 5.5 fl oz 500SC/A
Scab.
Disease occurs during cool periods. 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.
Rotate muskmelons with unrelated crops. Occurs primarily in late summer. Begin sprays when vines begin to run.
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 Quadris exists in the area, do not use Quadris. Use a fungicide from a different fungicide class.
Alternate:
chlorothalonil (Bravo, Echo, Equus)--2 pt 6F/A, or OLF (Use low rate early in season) alternate
with a tank mixture containing chlorothalonil or mancozeb and
Pristine 12.5-18.5 oz 38WS/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
Maganeze Toxicity.
This disorder occurs in acid soils (pH less than 5.8). Maintain soil pH at 6.5 to avoid toxicity.
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