Powdery mildew is an annual problem in fall grown cucurbit crops. Labeled fungicides usually provide acceptable disease control when applied on a 7 to 10-day frequency. But the fungus has developed resistance to several fungicides. And that can cause problems.

To address this, several new cultivars of pumpkin and squash with tolerance to powdery mildew were evaluated in recent trials at the Plateau Experiment Station in Crossville, Tennessee. 

In the pumpkin trial, Magic Lantern from Harris Moran, fared well, and is an excellent powdery mildew tolerant pumpkin. One acre of Magic Lantern was grown near the disease tolerant squash trial in 1999, and only a few plants developed mild symptoms of powdery mildew. The acre produced well and the fruit had excellent appearance.

Harvest, handling and storage tips for pumpkins

Now that you've grown your pumpkins it's time to give them the kid glove treatment. The soft touch is paramount because getting your product to market in good shape is key to making profits. Here are some harvest, handling, and storage tips to make sure your crop makes it to that sales display.

STORAGE

Pumpkins are subject to chilling injury at low temperatures and some cultivars cannot be expected to hold in good condition more than 2-3 months at 50-55 degrees.

However, Lil' Ironsides, by Harris Moran Seed Company, can hold well 4-5 months after harvest, this due to its thick-walled shell.

Use the following guidelines:

• Optimum temperature of storing pumpkins in the Mid-Atlantic region is 50-55 degrees.
• Optimum relative humidity is 50 to 70 degrees.
• Place the pumpkins on racks, in bins, or in baskets and hold in ventilated or common storage.

THE RIGHT VARIETY

Since many growers lack adequate labor and space to move pumpkins into curing and storage, the storage of pumpkins may not be feasible. There are some things, however, that can be done to maximize shelf-life and limit post-harvest losses. 

Since many growers lack adequate labor and space to move pumpkins into curing and storage, the storage of pumpkins may not be feasible. There are some things, however, that can be done to maximize shelf-life and limit post-harvest losses. 

Start with good quality pumpkins, such as those from Harris Moran like Magic Lantern, Lil' Goblin, Merlin. The variety is key because once harvested pumpkins don't improve in quality. Also, use cultural practices that contribute to quality fruit. For example, many research pumpkins are grown on hairy vetch mulch that is fall-seeded and killed with contact herbicides prior to planting. The thick mat of organic mulch keeps the fruit clean by limiting soil splashing in rains. It also allows growers or their customers to get into the field in wet weather for harvesting.

LONG, THICK HANDLES

Since handle strength and integrity are important, select varieties that offer long, thick  handles. Harris Moran varieties like Mystic and OZ fit this bill. Research has shown that a rigorous fungicide application program in the field during the growing season will contribute to stronger handles and longer storage after harvest. In general, smaller-fruited types have better handles than large, face-type varieties.

Many growers are now using long-handled loppers to cut stems from the vines at harvest. This takes little time and allows workers to pick up several fruit at a time after they are cut. The use of leather gloves also facilitates harvest, since some varieties tend to have strong, sharp spines on the stems. When handling or moving pumpkins, use as much care as possible to avoid physical damage. Throwing and dropping fruit can break off handles and cause puncture injury to fruit walls and other handles.

When it comes to pumpkin spacing, the squeeze play works

Research sponsored by Harris Moran Seed Company revealed that close in-row spacing results in a high number of fruit per acre without measurable reduction in pumpkin quality (size and appearance).

Dr. Ron Morse, research specialist at Virginia Polytechnic Institute,
conducted the effects of spacing on a semi-vining type pumpkin cultivar, Magic Lantern.

Six different spacing arrangements were set up to achieve different
plant populations.

Four replications were established: two at Glade
Spring and two at Hillsville, Virginia.

In 1999, all five high plants per acre spacings (treatments B through F) out-yielded the low plant per acre spacings by an average of 17%. 

Dr. Morse also points out that the more equidistant spacings (B and D) out-yielded a regular spacing of 8 x 2 by an average of 117% even though there were other treatments that had equal of higher plant populations. 

The data indicates that both plant population and arrangement of plants can affect pumpkin yield. 

In another study, Dr. Morse's research focused on nitrogen applications. Studies revealed that there was no significant difference in yield between the 201 lbs. and 401 lbs. rates. 

However sidedressing of N did increase marketable pumpkin yield by 30% as opposed to no N applied.

Excessive rates of N can result in decreased marketable pumpkins produced per acre, principally due to decreased fruit set and enhanced fruit rot.

Of Powdery Mildew and pumpkins

Powdery mildew is an annual problem in nearly every pumpkin growing area. Although it rarely destroys the crop, it seriously reduces yield and fruit quality.

Fungicides to control the disease are available, but they can be costly and often are not very effective, due to pathogen resistance.

Also, because of the long pumpkin growing season, it is difficult to get good chemical control, using ground equipment, without damaging the vines.

Harris Moran recognized the need for Powdery Mildew tolerant (PMT) varieties and, in 1987, made the first cross leading to the first PMT varieties. Within a very short time, these varieties have become a sensation in the industry.

HMS pumpkin varieties with tolerance to Powdery Mildew

• Magic Lantern F1
• Merlin F1
• HMX 6688 F1

We continue to emphasize Powdery Mildew tolerance in our breeding and plan to remain the leader for years to come.