VegNet Vol. 14, No. 29. Sepetember 19, 2007

Ohio State University Extension Vegetable Crops
On the WEB at:  http://vegnet.osu.edu

In This Issue

1. Preserving pumpkin quality

2. 2007 Illinois sweet corn hybrid disease nursery

3. Crop Reports

 

Preserving Pumpkin Quality

Sunburn: A stretch of 8-10 days of bright sunny, weather and afternoon temperatures in the upper 80’s has increased the chances of sunburn on ripe pumpkins still in the field. Pumpkins without irrigation and certain varieties seem more susceptible but all fruit can be affected. In some fields, damage can range anywhere from 5-10% to as high as 20%. If harvest is not in your immediate future, you still should maintain foliage cover with your disease control program in order to protect your fruit from the sun. The additional cost for more fungicide applications should be taken into consideration. Where the foliage can no longer provide protection from the sun, growers should consider harvest in the next few days.

Early symptoms start off as small dark red patches on the surface. These areas are slightly sunken.

Mature fruit with sunscald starting to develop

Area enlarges and starts to soften with secondary infection

 

Rind Damage and beetles: Growers should be checking pumpkin fruit about every other for feeding damage from cuke beetles and northern corn rootworm beetles. Their feeding on the rind of the fruit can cause significant injury making the fruit unmarketable. Major damage can take place in as little as two-three days. Pumpkin fields very close to corn fields seem to be most susceptible especially after a light frost that damages corn.

  

Above. Feeding Damage on pumpkin rind and Western, Northern, southern(spotted) corn rootworm as well as striped cuke beetle all feed on and cause damage to pumpkin rinds

 

Pumpkin Harvesting, Curing and Storage.  Here are some pointers on curing, handling and storing pumpkins and winter squash. Harvest fruit as soon as they are mature and prior to frost. Both squashes and pumpkins should be well matured before harvest and storage. In some years when maturity is late, pumpkin fruit with at least 40-50% of the fruit surface with orange color will continue to ripen. Use care in handling fruits to avoid wounds. Cuts and bruises in the rind are open to decay organisms that may cause a great deal of loss in the short run. Under proper conditions wound areas can heal over by producing cork tissue. The protective tissue seems to develop best at relatively high temperature and in moist atmosphere.

  • Harvest fruit when mature avoiding cuts and bruises.
  • Cure after harvest 80-85 degrees F and 75-80% humidity for about 10 days.
  • After curing, store at 50-60 degrees and 70% humidity.
  • Keep fruit dry and provide good air circulation.
  • Temperatures below 40 degrees for long periods cause chilling injury and lead to fruit rots.
  • Pumpkins will keep for 2-3 months

It is essential to keep the surface dry during the storage period. Any dry place where as close as possible to the desired storage temperatures can be maintained is suitable for storage of pumpkins and squashes. They keep best when not piled on top of each other but this is not practical for most operations. Try to keep stacks at minimum heights leaving room for good air circulation. Pumpkins will not keep so well as the hard winter squashes but pumpkins in good condition can be held 2 to 3 months without problems.

 

2007 Illinois sweet corn hybrid disease nursery reports by Jerald Pataky

[ Editor’s Note: It’s never too early to start planning for next season or perhaps you just want to forget this season. If you had problems with rust, Stewart’s wilt, MDM or other sweet corn diseases or just want to see how some varieties react to certain sweet corn herbicides, be sure to check out Dr. Pataky’s reports. If you do not have an internet connection, I can email you the reports or send you hard copies. The reports are too large to fax. I will also make the reports available at our website in the near future. Contact me: Bob Precheur, 2001 Fyffe Ct, Columbus, OH 43210, 614-292-3857, email: precheur.1@osu.edu ]

 

The summary of the 2007 University of Illinois sweet corn hybrid nursery is now available at www.sweetcorn.uiuc.edu  as Word or PDF files.  Table 3 which lists disease reactions and ratings for 249 hybrids in the 2007 nursery also is available at this site as an Excel file. 

In this year's nursery, hybrids were rated for reactions to three races of common rust (avirulent, G-virulent, and D-virulent), Stewart's wilt, NLB, MDM, SLB, and responses to two HPPD-inhibiting herbicides, Callisto (mesotrione) and Laudis (tembotrione).

 

Crop Reports by Brad Bergefurd 9/18/07 The cooler weekend temperatures were a welcome relief with temperatures north of I 70 dipping into the mid to lower thirties and mid to lower 40's south of I 70, though I have heard no reports of any frost damage to crops. However, the high temperatures and drought conditions are back again for southern Ohio growing regions today with very dry conditions and highs in the lower 90's.

Pumpkin harvest is in full swing.Some growers are reporting that, due to most all corn fields totally dried down now and corn harvest in southern Ohio going on since Labor day weekend, corn rootworm beetle adults have left the corn fields and are invading the green foliage in pumpkin fields and causing feeding injury to foliage and fruit, warranting insecticide applications. Corn rootworm beetles at first glance may look like cucumber beetles however upon closer observation one will notice less distinct stripes and a mottled pale to green or yellow coloration depending on species. For more information and pictures of the corn rootworm beetle adults see the OSU fact sheet http://ohioline.osu.edu/ent-fact/0016.html. Fungicides treatments continue in all vine crops to stay ahead of Powdery Mildew and Downy Mildew disease pressure, which seems to have weakened some the past 2 weeks. Harvest of sweet corn, ornamental corn, cabbage,tomatoes, bell and hot peppers, watermelon, cantaloupe,beans, summer squash,and cucumbers continues. Digging of potatoes and sweet potatoes continues with good size and quality being reported.

Growers are pulling tomato stakes and twine, picking up plastic mulch, main lines and trickle tape and beginning to chisel and plow fields and working ground and planting cover crops. Due to the high market price for wheat currently, wheat seed for cover crop is in very short supply and is very hard to find. Some annual rye seed carried over from last year is available from some sources.

The increased temperatures is a welcome for growers who recently planted plasticulture strawberries in the past 10 days even though with the dry weather and lack of rainfall, trickle irrigation is a must. Growers should keep an eye out for spider mites in strawberry crops especially in the drought stricken areas that have received little if any rainfall the past 3 months. For more information on spider mites in berry crops visit http://ohioline.osu.edu/b861/pdf/ch02_42-46.pdf .  Harvest of fall red raspberries continues in full swing with good demand. Some growers are reporting finding orange rust in wild brambles so remain on the lookout for this disease in black raspberry and blackberry plantings, the disease does not infect red raspberries. For more information and control measures for Orange rust in bramble crops visit Dr. Mike Ellis web site http://www.oardc.ohio-state.edu/fruitpathology/ and visit http://ohioline.osu.edu/hyg-fact/3000/3010.html . There are still some growers telling me they have a few extra strawberry plug plants available for planting or replanting give me a call for more information and availability.