VegNet Vol. 13, No. 13. July 26, 2006
Ohio State University Extension Vegetable Crops
On the WEB at:  http://vegnet.osu.edu
If experiencing problems receiving this fax, Call 614-292-3857

 

In This Issue

1.Powdery and Downy Mildew on Pumpkins

2. Crop Reports

3. What Are You Seeing

4. The 7 Day Outlook

 

Powdery Mildew and Downy Mildew Spotted on Pumpkins in Central OH  by Bob Precheur and Mac Riedel

Pumpkins planted in late May and early June were showing early symptoms of both Downy and Powdery Mildew last Friday. Since it is the last week of July, powdery mildew is arriving right about on time as in most years. Growers should consider starting their disease control program very soon.

Symptoms of Downy Mildew are very similar to Powdery Mildew. Downy mildew will cause the upper sides of leaves to yellow and brown out and produce grayish/white fungal masses only on the underside of leaves.

  

Downy mildew of pumpkin. Symptoms on upper leaf surface (left), and olive grey lesions underside of leaf (center) and typical symptoms in field on (right).

 

Powdery Mildew will produce white fungal masses on the upper and lower leaf surface and the stem ruining quality if left uncontrolled. Also if downy or powdery mildew cause high defoliation the fruit exposed to direct sunlight on hot summer days may begin to show symptoms of sunscald. Powdery Mildew will be more prevalent during drying weather; Downy Mildew will begin to show up more often during cool, wet weather. If downy mildew comes in then the weekly program should include a fungicide such as Tanos/Manzate, Previcur Flex + Bravo, or Gavel + Bravo alternated with Ridomil Gold Bravo or other fungicide with a different mode of action (different Fungicide Group). 

 

 

Powdery mildew pustules on upper leaf surface (left), and pustules growing together on upper leaf surface (right).

 

The first signs of powdery mildew are pale yellow spots on leaves, vines or petioles. These spots enlarge and become covered with white spores that appear powdery. Scout your fields by looking at the older leaves first although these symptoms can be found on younger leaves. Fields in low lying areas where mist forms and remains for long periods during the night are usually affected first. Make the first application when powdery mildew is detected in the area or is detected by scouting (one lesion on the underside of 45 old leaves). Once powdery mildew shows up, a good powdery mildew product should be included such as Flint, Procure or others. Nova is also recommended for control and rotation.

Consult the 2006 OH Vegetable Production Guide, Bull. 672 for recommended fungicides for pumpkins and other vine crops.

 

Crop Reports by Ron Becker and Mike Netz

Wayne County Report from July 24:

More cucumber fields in Wayne and surrounding counties are becoming infested with Downy Mildew.  It was also detected on a few summer squash plants on the farm we originally found it on three weeks ago.  We are also finding powdery mildew in many summer squash plantings.  Squash bug eggs are starting to hatch.  Other diseases being found on vine crops include phytophthora blight, angular leaf spot (mostly on older leaves) and anthracnose.

 

Rust is being found in sweet corn fields, with pustules starting to burst.  On 7/24 we also found sweet corn fields infested with fall armyworm with most fields having a 5-10% infestation, but one as high as 22%.  Though no ECB moths were found in our trap this morning, we did see moths flying around in potato fields.  Silk clipping by Japanese beetles and rootworm adults is light so far.

Tomato plantings are showing timber rot, early blight, septoria and bacterial speck on the leaves and stems.  Diseases found on the fruits have included bacterial speck, rhizopus rot and anthracnose.

In green beans, potato leafhopper and bean leaf beetles are commonly going over threshold.  Sclerotinia (white mold) is being found on green beans, cabbage and tomatoes (timber rot).

Ron Becker, Program Assistant, Agriculture and Integrated Pest Management, Wayne County

 

Nothern Ohio Report From July 21st.
Cucurbits

Most starting the second week of picking in pickles, haven't talked to anybody with enough labor! Mudding the pickle crop out during the first week of pick!

Pumpkins are later than normal, biggest ones just tipping & starting to run now.

Melons are a little behind also due to wet weather holding back plant growth & cool nights earlier. Lots of Angular Leaf Spot. Quite a bit of Downy Mildew. Other diseases: Alternaria, Gummy Stem, Anthracnose.

Insects include - cuke beetles, bean leaf beetles, heavy corn rootworm beetles in flowers

Peppers

Plantings made around the 1st of June now have decent fruit sets & blooming heavy. The crop has been unusually disease free so far, with only problems in areas where water stood! I have not seen any disease or bacteria yet - knock on wood!

Pale Striped Flea beetles have been bad over the last several weeks, low levels now.

Tomato

Can hardly find a field that doesn't have a wet hole in them. Early fields took the rains worse than the later planted fields. Harvest looks like it will start the 2nd week of August & there will be lots of sorting to do! Lots of disease !!

Wet areas have phytophthora root rot. Early Blight in most all fields. Septoria leaf spot firing up. Lots of bacteria - spot, speck & secondary canker. Spot is the worse, with most fields having it on the fruit already!

Cabbage

Yields in harvested fields are above normal. Some acres lost to water in almost every field, a few fields lost totally! Wet weather has caused a lot more disease than we usually see! Rhizoctonia, White Mold, Alternaria, Phytophthora root rot, Black Rot can be found quite easily! Downy mildew found for the first time that I know of!

Imported cabbage worms have been around since late April & continue to be the predominate worm! A few diamond backs only so far, usually by now they are a problem & seem unusually light this year. Had one hatch of a few cabbage loopers a couple of weeks ago. Thrips have not been a problem so far!

Mike Netz - Widmer & Associates Ltd. Gibsonburg, Ohio

 

What Are You Seeing?

Fields observations from growers and allied industry are welcomed anytime for inclusion in the newsletter. This is the kind of information that consultants, growers & processors are interested in and keep us ahead of developing situations that could affect our crops. Send me your observations by Wednesday noon each week. My email address is: precheur.1@osu.edu    My fax number is 614-292-3505. On your fax place my name so it gets to me. Looking forward to your observations.

 

The 7 Day Outlook

Cincinnati
Day Date| THU 27| FRI 28| SAT 29| SUN 30| MON 31| TUE 01| WED 02
Min Max

    Temp| 70  84| 72  83| 68  88| 70  92| 70  92| 69  93| 70  92
Wind 12h|  9  11|  8   9|  5   6|  4   7|  4   7|  4   6|  5   7
POP 24  |     88|     96|     60|     45|     39|     35|     35
 Q24    |      4|      4|      2|      0|      0|       |       
Clevland
Day Date| THU 27| FRI 28| SAT 29| SUN 30| MON 31| TUE 01| WED 02
Min Max

    Temp| 73  86| 72  87| 69  91| 72  90| 72  90| 70  92| 72  88
Wind 12h|  9   9|  7   9|  7   8|  6  10|  6  10|  6   9|  7  10
POP 24  |     78|     76|     43|     55|     37|     30|     37
 Q24    |      3|      4|      0|      1|      0|       |       
Columbus
Day Date| THU 27| FRI 28| SAT 29| SUN 30| MON 31| TUE 01| WED 02
Min Max

    Temp| 70  85| 71  84| 69  88| 72  92| 71  91| 71  92| 71  90
Wind 12h| 10  12| 10  10|  8   7|  7   9|  7   8|  6   8|  6   9
POP 24  |     84|     94|     56|     50|     36|     31|     35
 Q24    |      3|      4|      1|      1|      0|       |       
Dayton 
Day Date| THU 27| FRI 28| SAT 29| SUN 30| MON 31| TUE 01| WED 02
Min Max

    Temp| 69  83| 71  83| 69  88| 71  91| 71  91| 72  91| 71  89
Wind 12h| 11  11|  9   9|  7   8|  6   9|  6   8|  7   8|  7   8
POP 24  |     86|     91|     52|     45|     37|     34|     35
 Q24    |      3|      4|      1|      0|      0|       |       
Toledo
Day Date| THU 27| FRI 28| SAT 29| SUN 30| MON 31| TUE 01| WED 02
Min Max

    Temp| 71  89| 70  89| 68  94| 71  93| 71  93| 70  94| 70  91
Wind 12h|  9   9|  6   7|  5   8|  6   9|  5   9|  5   8|  5   9
POP 24  |     70|     59|     35|     48|     34|     33|     36
 Q24    |      2|      1|      0|      1|      0|       |       
Parkersburg, WV for SE Ohio
Day Date| THU 27| FRI 28| SAT 29| SUN 30| MON 31| TUE 01| WED 02
Min Max

    Temp| 69  86| 71  84| 68  84| 68  91| 68  91| 69  91| 69  92
Wind 12h|  5   9|  6  11|  5   3|  3   7|  3   6|  3   6|  3   7
POP 24  |     81|     85|     63|     46|     36|     35|     42
 Q24    |      3|      3|      1|      1|      0|       |      

Key

Min Max = daytime max and night minimum temperature for 24 hour period

Wind 12h = maximum sustained surface wind during 12 hour period.

POP24 = probability of precipitation for 24 hour period

Q24 = quantity of precipitation, QPF, for 24 hr period, see below:

 QPF Categories: 0 = no precipitation; 1 = 0.01 to 0.09 inches; 2 = 0.10 to 0.24 inches; 3 = 0.25 to 0.49 inches; 4 = 0.50 to 0.99 inches; 5 = 1.00 to 1.99 inches; 6 = 2.00 inches or greater