White onion facts for kids

Quick facts for kids White onion
White onions
Genus	Allium
Species	Allium cepa

White onions are a type of onion known for their light and mild taste. They are sometimes called "sweet onions." Like red onions, they have a lot of natural sugar and not much sulfur. This gives them their gentle flavor. Because of this, white onions don't last as long as some other onions. You can find white onions in many different foods, especially in Mexican and European cooking. People often add them raw to dishes like salads for a fresh, slightly sour, and mild crunch.

Taste and How We Use White Onions

White onions have a much milder taste compared to other onions like red or yellow ones. They are not as strong or "pungent." This is because they have more natural sugar and less sulfur.

Because of their mild taste, white onions are great to eat raw. You can find them in sandwiches and salads. If you chop raw white onion finely and soak it, it becomes even sweeter. It loses its slightly sharp or "astringent" taste.

White onions are very useful in cooking. They are often a key part of salads, adding a fresh taste without being too strong. They are also used in stews. Their light flavor doesn't take over the other ingredients. This helps all the flavors blend well together. White onions are also good in fermented foods like coleslaw. Their low sharpness allows them to become quite sweet in these dishes. They are also popular in salsas for the same reason.

Common Onion Diseases

Just like any plant, white onions can get sick. Here are some common diseases that can affect them:

Onion Smudge

Onion Smudge is a disease caused by a tiny living thing called a fungus. It can affect onions all over the world, at any stage of their growth. White onions are especially likely to get this disease. This is because their outer layers don't have much color. Colored onions have more natural chemicals that help protect them. Onion Smudge grows well in damp soil when the temperature is above 20 degrees Celsius. The fungus can stay in the soil, which means it can harm future onion crops.

This disease damages the outer layers of the white onion. This makes the onion look bad and lowers its value. If Onion Smudge isn't noticed early, it can spread to a whole crop. It can make the onion layers rot, cause early sprouting, and lead to other storage problems.

Onion White Rot

White Rot is a very serious fungal disease that affects most plants in the allium family. This includes garlic, leeks, and all kinds of onions. This fungus is special because it doesn't make many spores. Instead, it lives in the soil as hard little balls called sclerotia. These balls stay hidden in the soil for a long time, sometimes over 20 years. They wait for the right conditions to attach to a plant. Because they are so tough, many fields can't be used to grow onions for a long time after an infection.

White Rot can spread through a field or from one field to another. It can travel with flood or rainwater, on farm equipment, or with plant pieces blown by the wind. You might first notice White Rot when the oldest leaves of the onion turn yellow, wilt, and start to die from the bottom. A white, fluffy growth, called mycelium, might appear at the base of the onion bulb. This growth later forms the hard sclerotia balls. The fungus likes cool temperatures and becomes inactive when it's warm.

Botrytis Leaf Blight

Botrytis Leaf Blight is another fungal disease that mainly affects plants in the allium family, especially onions. This disease mostly harms the leaves of the plant. After getting infected, the leaves develop spots, also called "lesions." The plant's leaf tissue can also become soft and watery, leading to the leaves dying and looking unhealthy. The spots usually start as whitish marks, about 1-5mm long. They often have a light green, wet-looking ring around them. Later, the spots may sink in and look like straw, sometimes developing a slit. If a plant is badly affected, its onion bulb might be much smaller.

The Botrytis Leaf Blight Pathogen survives the winter as sclerotia, just like White Rot. These tough fungal masses spread the disease and can infect sprouted onion leaves and bulbs. Pathogens on the soil surface can also create asexual spores called conidia. These spores can then infect more plants. Botrytis Leaf Blight grows best in wet and cold weather, but it can still cause problems in other conditions.

Onion Downy Mildew

Onion Downy Mildew is a disease caused by a tiny organism called Peronospora Destructor. It affects the leaves, making them turn pale green, then tan, brown, or yellow, and finally collapse. This fungus spreads very easily among white onion crops. You might first see yellow patches in an onion field. These patches often follow the direction of the prevailing winds and get bigger as the disease spreads. On individual plants, you can see fine, furry, grayish-white growths. These growths can then get infected by other diseases, which might cause purple spots and dark spores.

The Peronospora Destructor pathogen only makes spores when it's living on a host plant. It releases spores at night when it's cold. These spores can easily be blown by the wind to infect other plants. The spores that survive the winter are called oospores. You can find them in volunteer onions (onions that grew by themselves), cull piles (leftover onions), and infected onion bulbs. This disease is found worldwide. It prefers humid places because it needs moisture to infect plants. It is most common in late Spring and throughout Summer.

How to Grow White Onions

There are a few ways to plant white onions:

• Onion Transplants: This is when you buy young onion plants, called seedlings, that have already started growing. You then plant them in your garden. This method often helps the onion bulbs grow quickly. However, these plants might be more likely to get diseases when they are fully grown.
• Onion Sets: These are small onion bulbs from the previous year's harvest that were not allowed to fully grow. They are dried and then planted in the current season. Onion sets usually grow the fastest and produce larger bulbs than onions grown from seeds.
• Onion Seeds: You can plant white onion seeds in late Spring. This method takes the longest for the onions to grow (up to 4 months for mature bulbs). But the onions grown from seeds are usually the least likely to get diseases.

Different types of onions need different amounts of sunlight to grow mature bulbs:

• Short-day onions grow bulbs when they get 10 to 12 hours of sunlight each day.
• Intermediate-day onions grow bulbs when they get 12 to 14 hours of sunlight each day.
• Long-day onions grow bulbs when they get 14 to 16 hours of sunlight each day.

For most white onion types, the best soil pH (how acidic or alkaline the soil is) is between 6 and 7. If the soil pH is below 5.5, the onions might not get enough magnesium and molybdenum. If the pH is above 6.5, there might be less zinc, manganese, and iron in the soil for the plants to use.