Why do cucumbers curl into a C-shape?
Most cucumbers grow in a straight cylindrical shape. Except when they don’t. Sometimes, a cucumber will curve into a C-shape. This is called cucumber fruit curl. It is also called crooking. There are many causes for crooking. Which one is affecting your fruit?
Some sap-sucking cucumber pests can cause crooking. This form of crooking is usually irregular, having been caused by thrip, mite, and whitefly feeding. Aphids, scale, and mealybugs can also cause this type of deformity.
Cucumbers are heavy feeders. They need nutrient rich soil and regular feeding to produce a healthy crop of uncurled cukes. You can side dress the vines with aged compost. This also acts as a mulch, which helps stabilize soil temperatures and reduces the need for added water.
Think about how much of a cucumber is water. Add the water needs necessary to grow the vines and you will see that cucumbers need a steady supply of water. This means watering regularly and consistently. If you have placed mulch around the vines, add water whenever the top inch of soil feels dry.
Hot weather/incomplete pollination
Hot weather kills pollen. This can mean the female flower did not get enough pollen to produce a properly shaped cucumber. This normally causes stunting or lopsided development, but it can also cause curling.
Newly forming cucumbers are easily pushed around by stems, leaves, and flowers, as well as the ground itself. Also, if the flesh is damaged early on in development, the damaged side may grow more slowly, causing a curled shape.
How to prevent crooking
A curled cucumber is fine to eat.
Cucumbers (Cucumis sativus) are a fruit from the gourd family (Cucurbitaceae).
Originally from South Asia, cucumbers have found their way into gardens around the world. Botanically, cucumbers are classified as berries because they are the fruit of a single ovary.
There are many types of cucumber: slicing, pickling, gherkins, bush, burpless, and seedless. Seedless cucumbers are a parthenocarpic cultivar, which means the plants develop fruit without being pollinated. These cucumbers are usually grown in greenhouses. All the other types of cucumbers are self-incompatible. This means they need to be cross-pollinated, from a different plant, for fertilization to occur. While any cucumber can be pickled, pickling cucumbers are bred for consistent size and shape, and they tend to have larger bumps. Varieties of pickling cucumber that perform best in the Bay Area include Pot Luck and Pickle Bush (good container plants), Saladin, County Fair 83, and Liberty Hybrid. Bush Champion, Parks Bush Whopper, Salad Bush and Spacemaster are good slicing varieties for containers. There are many good slicing varieties, including Marketmore 76, Marketmore 80, Dasher 11, Straight Eight, and Raider are good in-ground slicing cucumbers. New varieties are always being developed. In fact, I just discovered a Mexican Sour Gherkin cucumber that tastes like a cucumber but looks like a miniature watermelon!
How to grow cucumbers
Cucumbers love rich soil with a pH of 5.5 to 6.5, so moderate acidification may be helpful. Seeds should be planted 1 inch deep and 6 to 10 inches apart. After seedlings emerge, thin plants to every 12 inches. Cucumbers need lots of sunlight, so they are not the best choice for shade gardening. Cucumbers grow on creeping vines that can be trellised onto tomato cages, along fences, cattle panels, or on a teepee made from bamboo or other thin poles. Keeping your cucumbers off the ground will help reduce insect damage and fungal diseases.
Cucumber pests and diseases
Cucumbers have the same problems as other members of the squash family. Aphids, spider mites, whiteflies, nematodes, leafhoppers, leafminers, cutworms, squash vine borers, cucumber beetles, and squash bugs will all try to sink their tiny mouthparts into your delicious cucumbers, so keep a look out.
When you shop for cucumber seeds and plants, you may see an alphabet soup of letters on the tags. These letters are a shorthand for disease resistance. Common cucumber diseases that have resistant varieties include:
If you see AAS, it means All-American Selection, which is a plant that resists most diseases. Some diseases, such as sudden wilt, belly rot, and bacterial wilt do not have resistant varieties (yet). Many fungal and bacterial diseases can be avoided by waiting until leaves are dry before working an area. This reduces the likelihood of any diseases spreading to uninfected plants.
Cucumbers and bitterness
Sometimes, cucumbers can taste bitter. It was once thought that water stress was the only culprit, but research has shown that this bitterness is often caused by two genes that control the creation and inhibition of two compounds called terpenoids, which are more likely to occur when temperatures are lower than normal. Bitterness can also occur when plants are exposed to temperature fluctuations that are greater than 20 degrees F, or when they are stored next to other ripening vegetables.
Cucumbers and cross-pollination
Cucumbers of differing varieties or cultivars can cross-pollinate. Although cucumbers are members of the gourd family and cousin to melons, squash, and pumpkins, they cannot cross-pollinate with these varieties.
Increase pollination and fertilization rates by planting flowers near your cucumbers. This will attract more honey bees and result in larger yields.
Cucumber mosaic is caused by a virus called Cucumber mosaic cucumovirus (CMV). This pest has the widest global host range of any plant virus.
It is mostly spread by aphids, but this disease can also be carried on shoes and garden tools and by seeds. It is most commonly seen on all cucurbits, except watermelon.
Symptoms of cucumber mosaic
Young infected leaves tend to cup downward. Mature leaves become severely mottled with light and dark green patches. Leaf midribs may become deformed with a zigzag growth. Due to the interference of photosynthesis, growth is stunted and fruits can be deformed with bumps. Cucumber mosaic can cause cucumbers to turn white.
How to control cucumber mosaic
As prevalent as the mosaic virus is, planting resistant varieties is the best control. Once an outbreak occurs, all affected plants should be removed and thrown away. A reflective mulch can be used to repel aphid vectors. Chemical pesticides and insecticides have not been proven effective against cucumber mosaic.
Spring is the time of year when it is common to see a white powder appear on the leaves of cucumber, melon and other cucurbits. You may also see it on tomatoes, roses, snapdragons, chrysanthemums, peas, artichoke, beets, grapes and practically everything else. This bane of gardeners is called powdery mildew.
What starts as a small white spot, powdery mildew expands to engulf an entire leaf as the nutrient-sucking fungi bleed the life from your garden. It can be found on either side of a leaf and sometimes on stems.
Powdery mildew is a fungus. It is caused by different types of fungi (e.g., Erysiphe spp., Sphaerotheca spp.), depending on which plant is affected. Contrary to common belief, moisture and humidity are not needed for these fungal beasties to appear.
Powdery mildew fungi simply need living plant tissue to survive and thrive. To make matters worse, their spores are carried on the wind, so the battle never ends. The reason powdery mildew seems to disappear in the heat of summer is that these microorganisms prefer shade and temperatures between 60° to 80°F. Our California summers are simply too hot for the spores to reproduce. Instead, they remain dormant until conditions improve.
The white powder seen on leaves is actually thin layers of fungal tissue (mycelium). Other symptoms of powdery mildew include:
Not only does powdery mildew cause leaf loss, it can also weaken a plant. This lowers production and increases susceptibility to other pests and diseases, such as Citrus Blast. Leaf drop can also lead to sunburn damage.
Prevention and vigilance are the best ways to counteract powdery mildew. These tips can help, but nothing will eliminate powdery mildew in the garden:
Now, some people recommend spraying plants with a baking soda and water spray. I have had mixed results, but other people swear by it.
The bright orange flesh of butternut squash is a primary ingredient in rich, creamy soups, substantial casseroles, and delicious pies! This winter* squash can be stored for a surprisingly long time, plus, it’s easy to grow! This plant is a no-brainer. Once it gets going, you can pretty much ignore it until harvest time.
*Squashes are classified as either ‘summer’ or ‘winter’ varieties. This has nothing to do with when they are grown, Rather, it relates to when they are eaten. Winter squashes have thick, heavy duty skins that allow you to store them for several months. (I’ve stored some successfully for over two years!)
Butternut squash lifecycle
Butternut squash is a member of the cucurbit family. Cucurbits are unique in that they produce both male and female flowers on the same plant. Insects, especially bees, are attracted to the large, showy blooms. As these beneficial insects travel from flower to flower, pollination occurs. Female flowers can be identified by the immature fruit seen at the base of the flower. Male flowers have a ‘beard’ at the base that easily breaks off. (Male flowers can be deep fried, stuffed with cheese and baked, or sautéed in an omelet!)
How to grow butternut squash
Butternut squash grows best in full sun, though I have grown abundant crops under well-pruned fruit trees. This is a deep-rooted plant, making it well suited to areas experiencing drought. Butternut squash does not need particularly fertile soil and it can go weeks without watering. If larger leaves start to wilt, water deeply. There is no need to fertilize butternut squash.
Pests & diseases of butternut squash
Butternut squash is prone to root rot, so avoid overwatering. Seedlings are susceptible to damping off disease when the soil is too cold or too wet. Slugs and snails, caterpillars, and cucumber beetles will attack young plants. Later in the season, aphids, spider mites, and whiteflies can cause problems. Powdery mildew and other fungal diseases are common, but they rarely kill the plant or harm the fruit.
This is one of those ‘partly true, partly myth’ situations in the garden. Traditional folklore warns gardeners against growing squash, cucumbers, and melons near each other. The claim suggests that cross-pollination will occur, affecting the taste of the produce. Since pollination can only happen with pollen of the same species, this cannot really happen. What can happen is cross-pollination between varieties of the same species. Cucumbers and melons are a different species, so they will not cross-pollinate with each other or other members of the cucurbit family.
Summer squash, pumpkins, gourds, and some winter squash, all being members of the same family, can cross-pollinate. This pollination will create viable fruit identical to the mother plant. The genetic changes can only be seen in the seeds that are produced. If you save seeds like I do, this may result in something really unique growing next year. Sometimes it will be edible and sometimes it won’t. Butternut squash will cross-pollinate with pumpkins, so you’ll want to keep them as far apart as possible. Oddly shaped fruit and poor taste are usually the result of over-fertilized soil, too much irrigation, or damp weather, and not weird cross-pollinations.
Harvesting & storing butternut squash
The more often you harvest the fruit, the more fruit the plant will produce. In the plant world, reproduction is the name of the game. Fruits can be eaten right away or allowed to dry out, or cure, for later use. Fruits can be allowed to cure on the vine or removed and stored in a cool, dry location.
Have the pea plants in your garden turned white?
If you look at the photo below, you will see that new (uninfected) growth is bright green, as it should be. Everything else on the plant looks bleached. That bleaching is caused by a fungal disease known as Fusarium wilt.
Similar to Verticillium wilt, Fusarium wilt is a common vascular disease in which a fungus (Fusarium oxysporum) clogs vascular vessels. It’s pretty much the coronary artery disease of the plant world. In addition to bleaching, common symptoms of Fusarium wilt include chlorosis, stunting, damping-off, brown veins, necrosis, and premature leaf drop.
This soil pathogen is found worldwide and it is spread by water splash, tools, and infected seeds and transplants. Fusarium wilt enters a healthy plant when germinating spores (mycelia) stab at the plant’s root tips and any damaged root tissue. That’s where the really amazing stuff starts to happen!
Fungal life cycle
The Fusarium oxysporum fungus has no known sexual stage. Instead, it produces three different asexual spores: microconidia, macroconidia, and chlamydospores. Basically, the germinating spores (mycelia) inject themselves into a plant’s root system. From there, the mycelia move through the cells of the root cortex and into the xylem (a plant vein). Then, it starts producing the microconidia (asexual spores). The microconidia join the sap stream for a free ride to the rest of the plant. Eventually, there are so many microconidia that a vein is blocked. That’s when they germinate.
The vein blockage stops the plant form absorbing and moving nutrients, so the stomas close, the leaves wilt, everything looks bleached and it dies. As the plant dies, the fungus spreads throughout the plant and sporulates. [Cool word, right? It means “to produce spores”]
Plants affected by Fusarium wilt
Fusarium wilt attacks a variety of garden plants and the pathogens are specialized according to the victim. Fusarium wilt can attack peas, beans, and other legumes, tomatoes, tobacco, sweet potatoes, cucumber and other cucurbits, and even banana plants!
Fusarium wilt controls
Once a plant is infected with Fusarium wilt, there is nothing to be done except remove the plant and toss it in the trash. Planting resistant varieties in the garden can help prevent Fusarium wilt, but crop rotation is not an effective control method. This is because the chlamydospores can hang out in the soil for a long time. Some fungicides can be marginally effective.
Since Fusarium oxysporum prefers heavy, moist soil, aeration and adding compost to the garden can bring more oxygen into the soil. This reduces the welcome mat effect for many types of fungus. Ensuring proper drainage is the best way to avoid this garden menace.
You can grow a surprising amount of food in your own yard. Ask me how!
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