by Sally Colby
Beit Alpha cucumbers are becoming more popular among growers, and for good reason. They’re gynoecious (produce only female flowers) and parthenocarpic, so they don’t require pollination. With good management in a high tunnel, these seedless cukes will produce two crops in one season, and skilled growers can usually manage pests through biological methods. Steve Bogash, Penn State Extension horticulture educator, conducted research on growing cucumbers in a high tunnel. He made a few modifications to a 17’ x 48’ tunnel, including a small fan in the peak for ventilation and thermostatically controlled louvers in one wall to keep heat out of that section of the tunnel. He noted that the rolled-up sides of the tunnel tended to trap heat at the top, resulting in temperatures of up to 125 degrees, but the ventilation efforts paid off. “This is one of the easiest conversions I’ve ever done in any house,” said Bogash as he talked about the two-year trial. “One of the things I like about this is how fast you can turn a crop around. The trend for growing ornamentals is down, so what can we do with that greenhouse space?” For the trial, Bogash used a high-coir mix in buckets, and used the mix more than once. “We always tell growers to not reuse mix,” he said. “My goal was to see how cheaply I could do this, so I grew multiple crops using the same mix. When you use a high-coir mix, the structure holds up well and we could reuse it without it becoming waterlogged.”
In the first year of his study, Bogash allowed every vine to grow without pruning. “I kept every vine, and kept clipping them up,” he said. “It was an absolute jungle in there. I lost control in my second (fall) planting – I lost control over aphids, spider mites and powdery mildew because I couldn’t spray.” Although the vines were still producing well up until that point, there was no way to effectively spray with such thick growth. In the second year, Bogash limited the growth to a single vine until each one reached the purlins. “Where we had side shoots coming out, I allowed one side shoot with a flower, then cut it off there. Once it hit the purlin I let it hang – you’re way into production at that point.” Bogash compares the growth habits of field grown cukes to those grown in a greenhouse. “In field cucumbers, it’s typical to get three to four weeks of good production, then the vines start to senesce,” he said. “No matter what you do, no matter how much fertilizing you’re doing, no matter what the level of insect and disease control, once the vine reaches three to four weeks of production, you need to have some other plants going.” By the time it became obvious that the vines should have been thinned, it wasn’t worth the time because there were only a few more weeks of harvest before the vines started to decline. “That made a huge difference in spraying,” said Bogash. “In both early and late plantings, I was able to keep complete control of aphids, spider mites and downy mildew – all of the typical indoor pests.”
For spring plantings, Bogash established one plant in each bucket; for fall plantings he allowed two plants in a bucket with an extra string. “Two plants was better,” he said. “Because we’re thinning them to one stub when the vines take off, it worked real well. We doubled the population and I had no problem keeping them sprayed.” Bogash tried transplanting, and found that it wasn’t worthwhile. “You lose very little time with direct seeding,” he said. “The plant is up in seven days, the plants are easier to clip and there’s a lot less stretching.” With fall-planted cukes, Bogash’s goal was to double the population. “I was doing everything ‘wrong’,” he said. “I was using ‘used’ soil. I put four seeds in every pot, figuring I’d thin them back to two, but I got 100 percent germination without any damping off.”
Bogash lists some of the Beit Alpha varieties that worked well in his trial. One is Socrates, which Bogash harvested a little larger than usual. “I like them because they have a thin, palatable skin that doesn’t need to be peeled,” he said. “They have a generally a smaller seed cavity.” Bogash noted that the limitation with Beit Alphas is the market – consumers are sometimes reluctant to purchase them because they don’t look like a traditional cucumber. Rocky, a blocky, stout cucumber has been replaced by Unistar and Iznik; all considered mini cukes. They can be harvested at three to four inches, but require refrigeration to maintain quality for more than a few hours post-harvest.
Bogash refers to Picolino, another Beit Alpha type, as a good choice for growers whose can only select a few varieties to grow. “It comes in a week earlier than Katrina, which is my other number one Beit Alpha,” he said, “and stays in production for six to seven weeks before the vines start to collapse. Katrina has a pleasing shape and is barely ribbed, which gives it added market appeal.”
For growers who aim for the traditional market and are trying to provide cucumbers before field cucumbers hit the scene, Corinto is a winner. “The yields are excellent,” said Bogash. “It’s a heavy cucumber and we had a very low cull rate. For a parthenocarpic, indoor cucumber, it’s a very aggressive vine and the fruit are consistent.” Bogash says that it’s important to prevent pollination to avoid crooks and culls, which he accomplished with screening. “I used regular window screening, and on the roll-up sides with the wiggle wire, I took the wiggle wire off and hung window screening,” said Bogash. “I taped it at the bottom and was able to keep most of the pollinators out.” Bogash says that the additional benefit of the screening was that it kept cucumber beetles out. “Here’s the challenge: when you spray for cucumber beetles, you’re typically going to use a pyrethroid, which are successful for controlling cucumber beetles but they also kill the predators. Then aphids move in and you have to spray with an aphicide, and you’re stuck in a loop where you’re killing cucumber beetles and aphids.” Bogash says by eliminating entry points for cucumber beetles through screening the house, growers can keep aphids, thrips and spider mites in check; and potentially manage pests with biological controls.
Success with Beit Alpha cucumbers
by Sally Colby