Bug-Resistant Summer Squash Substitutes
Tromboncino Squash. Southern Exposure Seed Exchange
Most summer squash and zucchini are in the species Cucurbita pepo. They are easy to grow —the main challenges are pests, diseases, and moderating the quantities available. These crops can crank out high yields of a vegetable almost everyone likes.
Where insects are a problem for summer squash, vigorous plants of other squash and gourd species can bear all season in those areas. Growers with bad pest problems can try:
- Tromboncino squash (60d OP), a C moschata squash; Light green fruits grow long, curving to a bell at one end. Vigorous vining plants that can be grown on a trellis. Harvest at 8”-10” (20-25 cm) long when the flavor is fine and sweet. Southern Exposure Seed Exchange. On the coast of France and Italy, Tromboncino d’Albenga and Trompette de Nice were traditionally grown as summer squash and a few fruits left to ripen for winter storage.
- Zucchino Rampicante (60-70d OP) C moschata; Italian heirloom, vigorous vining squash; long slender 15” (38cm) fruit with a bulb at the bottom. One of the best eating summer squash: very tender, mild tasting. The long neck makes great slices with no seeds in them! Insect and disease resistant. Baker Creek.
Rampicante squash. Baker Creek - Tromboncino and Rampicante are closely related, if not the same.
- Long de Nice (C moschata); Fruit range in size between 10-20 lbs (4.5-9 kg) each with a long neck and fine-grained flesh with few seeds. Vines spread at last 15ft (4.5m), consider trellising. One or two full-grown squash per vine, but you’ll get more if you harvest them immature. Generally not as long as Rampicante or tromboncino. Baker Creek
Long de Nice squash. Baker Creek - Luffa (Luffa acutangula and aegyptiaca vegetable sponge, 65d OP, zones 7-13), Very long vines, consider trellising. Tastes similar to summer squash when harvested at 4” (10cm) for eating raw, pickled, cooked with other vegetables. The mature fruits are harvested when the skins dry brown, to use as vegetable bath sponges or pot scrubbers, with an incidental seed harvest at the same time.
Maturing Luffa. Seed from Survival Garden Seeds - Cucuzza (Lagenaria siceraria, snake or serpent gourd, 60-75d OP grows in zones 2a-11b.) Cucuzza edible gourds have more resistance to squash bugs. Just be sure to harvest them relatively small (while skins can be pierced by a fingernail, 12” (30cm) max) for good flavor. These are very vigorous, sprawling plants, which, happily, are also prolific. One option is to plant a row of regular zucchini alternating with these bigger plants —when the zucchini succumb to disease, the sprawlers will take over. Vines can reach 25’ (7.6m)
Cucuzza Seeds from Italy.
Growitalian.com - Lunga Da Pergola (Lagenaria siceraria, 60d to 6” (15 cm) fruit). Edible gourd, vigorous vines. At its best small, about 6” (15cm) long, when fruits will be slightly sweet and tender. Fruit can grow up to 5’ (1.5 m) long. A very productive strain with white mottling on the gourd and leaves.
Serpent Gourd Lunga di Pergola. N E Seeds
Some zucchini varieties are especially attractive to cucumber beetles and may be grown as a trap crop: Cocozelle summer squash, Seneca, and Dark Green zucchini. When beetles accumulate in the trap crop, flame it or till it in.
Crop Requirements for Squash and Gourds
Summer squash thrives on high levels of organic matter. Although only a light to moderate feeder for nitrogen and phosphorus, it requires quite high levels of potassium. Foliar seaweed spray can be used to make up for nutrient deficiencies. This crop does best with plentiful, but not excessive, moisture. That said, be careful not to overwater the seeds before they germinate, or they will rot.
This frost-tender warm-weather crop germinates at 60°F (15.5°C) minimum and does best at 85°F (30°C). Germination takes 5–10 days. During growth the ideal temperatures are 75°F–85°F (24°C–30°C) in the day and 65°F (18°C) at night.
Sowing Squash and Gourds
Seed can remain viable for up to 5 years, if stored in a cool, dark, dry place. Seeds should be sown 0.5″–1″ (1–2.5 cm) deep, 6″–12″ (15–30 cm) apart, in widely spaced rows if you are not trellising. Sow deeper in hot weather, when it helps to turn on the drip irrigation, and sow each seed right by an emitter. Water at sowing, then not again until seedlings emerge. For a slightly earlier harvest, you can pre-sprout the seed.
Covering the row with netting will keep the pests away. If possible, use hoops or a rope above the row, pulled taut between stakes, to hold the netting above the leaves, as cucurbits are susceptible to abrasion damage. Remove the netting as soon as you see female flowers, to allow for pollination.
Transplanting Squash and Gourds
When transplanting squash, take care to disturb the roots as little as possible. If you sow 2 seeds in each cell, be sure to pinch off the smaller one as soon as possible to remove the competition.
As soon as the plants have one or two true leaves, at about 3–4 weeks of age, transplant in a mild spell, burying the entire stem below soil level, up to the seed leaves (carefully!) to protect it from damage. Cucurbits started indoors grow long spindly stems, which are quite fragile. Make the hole deep enough, slip the plant out of the container, perhaps on the blade of a knife, pop it into the hole, and close up firmly.
Plant 2’–3′ (60–90 cm) or more apart in the row. Transplanting allows a crop to be established earlier than would be possible with direct sowing in spring. Alternatively, a crop can be gained from a summer window in the planting schedule for a bed, after an early spring crop. Transplants do not grow as sturdy a root system as direct sown squash do, so I would not recommend transplanting if direct sowing is possible.
Pests of Squash
Squash bugs are probably the most common pest. The adults are long gray insects that emerge from overwintering in wooded areas once temperatures reach about 70°F (21°C). They are more attracted to pepo squash than they are to moschatas. Plants attacked by squash bugs look baked to a crisp, with curled bronzed leaves. Squash bugs can do a lot of direct damage to leaves, and they also vector yellow vine disease. They feed on young seedlings for preference and lay groups of spaced bronze eggs on the undersides of leaves. The eggs hatch in 10 days, and the nymphs suck sap from the plants. There are many generations each year, and numbers quickly build. Drop handpicked adults into soapy water rather than crushing them as the smell of the crushed bugs attracts more. It is also possible, but not easy, to crush the hard-shelled eggs. An alternative is to tear off egg-covered leaf pieces and drown the eggs in soapy water. Squash bugs can be trapped overnight under boards on the soil near the plants —in the morning, lift the boards and collect the bugs.
For more info on squash bugs, see the ATTRA publication, Squash Bug and Squash Vine Borer: Organic Controls, that includes pest lifecycles, systems-based management practices, mechanical and physical practices, and biological and botanical controls. Buckwheat can be interplanted to attract tachinid flies that parasitize squash bugs.
Striped cucumber beetles are our worst pests some years, even compared to squash bugs. In the hoophouse, we handpick the adults inside squash flowers in the mornings while they are still sluggish. Long pointed tweezers are our tool of choice. Our hope is that, by battling this first generation, we will reduce numbers for the rest of the season. To attract beneficial insects that are predators or parasites of the cucumber beetle, grow buckwheat, cilantro, dill, or winter peas near the squash plants, timed so that they flower when the rowcover or netting is removed from the squash plants. Another method of reducing pest attacks, especially useful after flowering, is Surround kaolin clay spray. It does need renewing after rain or overhead irrigation. If all else fails and action is imperative, Spinosad will kill them (and some other insects too).
The adult squash vine borer is a fairly large orange-and-black fuzzy moth with glassy black wings. It is active in May and early June, and there may be a second generation in late July/early August. The small flat brown eggs are laid singly at the base of the stem. The larvae hatch after 1 week, and are white with a brown head. They spend 4–6 weeks in the stem, eating upwards and growing to 1″ (2.5 cm) in size. Then they dig into the soil and pupate for the winter.
Plant symptoms include wilting of the whole plant and stem holes surrounded by frass (caterpillar poop). To save the plant, act at the first sign of trouble and pick out the grub, then pile soil over the injury to help the plant recover. Injecting Bt (Bacillus thuringiensis) into the stem is another solution. For prevention, rotate crops and use netting or rowcover over plants until flowering. Another technique to try is pinching out the growing tips of the vine when it is 1’–2′ (30–60 cm) long, which causes the plant to branch and increases the odds that some part of it will survive.
Diseases of Squash and Gourds
I haven’t yet done a Plant Diseases of the Month Series, so I’ll include info here.
- As always, aim to avoid diseases by ensuring good air flow and appropriate water levels.
- Powdery mildew (PM) (a white coating starting on older leaves) is a common fungal disease in hot dry weather. Drip irrigation helps reduce the spread of PM, compared to overhead irrigation.
- Downy mildew (yellow angular spots with leaf curling and a purplish cast to the undersides of leaves) happens in cool wet weather late in the season, and plants can recover if the weather heats up.
- Anthracnose (dark brown spots on the leaves and round sunken spots on the fruit) is a fungal disease worse in warm wet weather from mid-season onwards.
- Angular leaf spot, Pseudomonas syringae pv. lachrymans (browning of the leaf between the veins and small round spots on the fruit) is a bacterial disease more common in cool damp weather. The symptoms can resemble those of downy mildew.
- Black rot/gummy stem blight (Didymella bryoniae) is a fungus occurring with wet soils, in wet weather (cool or warm).
- Mosaic viruses can be spread by aphids. Succession cropping helps evade these.
- Bacterial wilt (Erwinia) causes sudden dramatic wilt and death of the whole plant. It is spread by cucumber beetles.
This post is adapted from a chapter in my second edition of Sustainable Market Farming, with some additional information on squash varieties.
