Nothing can beat Elizabeth Taylor’s shrieks of rage when it comes to shrews, but you might not want them in your garden. Then again, you might.
Shrews are found everywhere except in Australia, New Guinea, and New Zealand. There are 385 known shrew species and an estimated world population of 100 billion, so they are probably closer to your garden than you realize.
Shrews may look like mice with long noses, but they are more closely related to hedgehogs and moles. They tend to be grayish-brown. Some shrew species have stumpy tails while others have longer ones. Unlike a mouse’s gnawing teeth, shrews have sharp, predatory incisors in front and grinding molars in the back. Most of these creatures are tiny. The Etruscan shrew, native to Eurasia, is less than an inch and a half long and weighs 1.8 grams. [An American nickel weighs 5 grams.] Asian house shrews are the largest species, weighing in at 100 grams and 6 inches long.
Shrews are like hummingbirds in that they eat almost constantly. Captive shrews eat as much as two times their body weight each day. They push their way through leaf litter looking for beetle larvae, caterpillars, centipedes, grasshoppers, grubs, slugs, and sowbugs. They also eat carrion and occasionally frogs, fruits, mice, nuts, and seeds. Shrews have been known to live in beehives and eat the bee larvae, though how they survive the stings is beyond me.
With so many shrew species, some variation in lifecycle is to be expected. For the most part, however, females have two or three litters each year. These litters are usually found in a burrow borrowed from some larger creature, or tucked away under a rock. Young are born blind, deaf, and hairless. Within a month or two, those young are sexually mature, but they generally don’t live longer than a year or so.
Most shrew species are solitary creatures except when breeding or raising young, but the American least shrew shares its food and shelter with neighboring shrews. Solitary or social, shrews hoard food but they do not hibernate in winter. Instead, they take more drastic steps to survive periods of cold. Unlike bears, who mostly sleep through the cold months, shrews enter a torpor in which they shrink their bones and organs by 50% to survive winter. [No wonder they eat so much!]
Shrews don’t see very well, but they have excellent hearing and smelling abilities. Some shrew species even use echolocation to get a sense of their surroundings. The American least shrew also has venomous saliva that it uses to defend itself. The Eurasian water shrew and the short-tail shrew have venom that can paralyze small prey. Nearly all shrew species have nasty scent glands that can really stink up a place. If you want to keep the potential stink away from your home, be sure to keep plants and mulch from providing shrew shelter near exterior walls.
When it comes to mammals in the garden, it ends up that shrews are beneficial helpers that keep many pesky insects in check.
Potato virus Y (PVY) is the Big Daddy of potato problems, right up there with early blight. And potatoes aren’t the only plants at risk. Peppers, tomatoes, and groundcherries can all catch PVY. Losses can be as high as 80%. Infected potatoes that make it to harvest don’t last in storage. And who wants to eat an infected potato?
Potato virus Y is spread by aphids, but not in their saliva. Instead, these microscopic potyviruses stick to aphids’ mouthparts (stylets). As the vector aphids feed, they spread the disease. Your shoes, clothes, and garden tools can also transfer this virus.
The many flavors of PVY
PVY used to be easy to identify. This meant infected plants were removed right away, and the spread of disease was limited. Like another virus that shall remain unnamed, the PVY virus has been mutating a lot lately, making it more difficult to manage. Recent mutations have fewer symptoms, making infected plants harder to identify. They stay in place longer, increasing the spread of disease to nearby plants.
The most common variations of PVY include PVYO (ordinary), PVYC (uncommon), PVYN (necrotic), PVYNTN (tuber necrosis), and PVYN-Wi (a recombinant strain). The tuber necrosis strain can cause potato tuber necrotic ringspot disease (PTNRD). Botanists sure do like their acronyms, don’t they?
Potato virus Y symptoms
Brown spots on leaves and tubers are the first sign of potato virus Y infection. Other symptoms vary depending on the plant age and health at the time of infection, environmental conditions, potato cultivar, soil health, virus strain, and the presence of other viral diseases, such as PVA, PVS, and PVX. Chlorosis, curved midribs, leaf crinkling, mosaic, mottling, and vein distortions are early signs of PVY. Infected leaves feel rough (rugose) compared to healthy leaves. If you look on the underside of infected leaves, you will see dark lesions and black streaks on the midrib. As the disease progresses, leaf loss and stunting are common. This disease is easily mistaken for calico (alfalfa mosaic virus).
Potato virus Y management
Chemical treatments are not effective against potato virus Y, so these good cultural practices are your best line of defense:
Potato virus S symptoms
According to the International Committee on Taxonomy of Viruses, potato virus S may cause small, necrotic lesions. Other sources say that you may see some of the same symptoms as in potato virus A, such as mild mottling, open growth, rough leaves, and sunken veins. You may also see bronzing if the infection occurred early enough in the season.
How potato virus S spreads
This virus is spread by aphids, especially green peach aphids (Myzus persicae) and potato aphids (Macrosiphum euphorbiae). It can travel on shoes, clothing, and garden tools. It can also occur on other host plants that may be a little too close to your potato patch.
Cleveland’s tobacco (Nicotiana clevelandii), white goosefoot (Chenopodium album), and Widow’s tears (Tinantia erecta) can act as hosts for this virus, so you may want to keep them away from your quinoa and potatoes.
Chemical treatments are ineffective, but horticultural oils may provide some protection. The best way to avoid potato virus S is to invest in clean seed potatoes and sanitize those garden tools regularly.
For lack of a better name, potato virus A (PVA) can infect more than just potatoes. Eggplant, peppers, and tomatoes are also susceptible.
Potato virus A is usually a mild problem, but it can cause crop losses of up to 40%. This disease is worldwide, and it combines readily with potato virus x (PVX) and potato virus y (PVY). When this happens, losses can be catastrophic. In the world of potato viruses, PVA is ranked 5th behind potato leafroll, PVY, PVX, and PVS.
The PVA virus
This little potyviral RNA strand is tricky. There are many different strains, and each one has slightly different symptoms and behaviors. This can make diagnosis difficult. This viral disease is spread by infected seed potatoes, mechanically, and by aphids. Once infected, aphids carry the potyvirus in their gut. As they feed, they spread the disease through their saliva. Your shoes, clothing, and garden tools can also carry PVA into your potato patch.
Symptoms of potato virus A are faint and can easily be missed. Mild leaf crinkling and yellow mottling might be all you see. If you look more closely, you may see these other symptoms:
Stems of infected plants commonly bend outward from the center, giving them a bushier appearance. Depending on the cultivar, the degree of infection, and environmental conditions, complete leaf death may occur.
The best way to prevent this disease from occurring in your garden is to only plant certified disease-free seed potatoes with a reputation for being resistant to PVA. After that, control aphid populations. As any gardener knows, aphids are highly prolific. You can reduce their numbers by avoiding the use of excess nitrogen, planting as early in the season as possible, and monitoring for vanguards. A single aphid can turn into thousands of aphids in a few short days.
Infected plants should be removed immediately and thrown in the garbage bin. As always, disinfect your garden tools regularly with a bathroom cleaner.
And don’t let the threat of disease stop you from trying your hand at growing potatoes at home. They are easy to grow and taste delicious.
Potatoes come many of colors: blue, purple, red, yellow, and white. But why does potato skin turn green sometimes, and can it hurt you?
The simple answer is yes. Green-skinned potatoes can make you sick. According to WebMD, you can peel green-skinned potatoes, but those potatoes are still not entirely safe to eat. It’s all about toxins.
Like other members of the nightshade family, potatoes produce toxins. The toxins produced by potatoes are called solanine and chaconine. These toxins are part of a potato plant’s defense mechanisms. They are produced in abundance when tubers are exposed to light. The green color under a potato’s skin is chlorophyll. You can use it as a signal that lets you know a spud’s chemistry has changed.
Why do potato skins turn green?
Tubers belong underground. Uninjured potatoes are relatively stable in cool, dark locations. Expose them to light once and nothing happens. Expose them to light several times and things start happening. Imagine, if you will: First, they get dug up at the farm and see daylight for the first time. They get moved to a shipping truck and roll down the freeway with more sunlight. Drop them off at the processing plant and they get more light. You get the idea. By the time they leave the grocery store (where they got even more light) and arrive at your kitchen, some of those potatoes will have shifted from storage mode to growth mode. That’s when trouble starts.
Is peeling enough?
Many people say that peeling the green skin away makes the spud safe to eat. That’s not entirely accurate. While most of those toxins are stored in the skin, they are still present in the rest of the potato. Just as a moldy cheese will also have mold growing throughout its interior, even if you can't see it. Peeling a green-skinned potato may not be enough. And cooking them does not affect the toxins.
All that being said, if you are generally healthy with a good digestive system, you may be fine with an occasional green-skinned potato. If you notice any of these symptoms, however, see a doctor:
Preventing green-skinned potatoes
You can’t control what happens to your potatoes before they arrive at your home (assuming you haven’t started growing your own yet). What you can do is store your potatoes in a dry, cool location with as much darkness as possible. Your refrigerator or pantry are ideal.
If an occasional green-skinned potato appears, throw it in the trash if it was from the store. If it was homegrown, you can.add it to the compost pile or plant it instead of putting your tummy at risk.
Powdery scab may sound like an adolescent skin problem, but it is a disease of potatoes that leaves them looking, well, scabby. You can cut away the affected bits and eat the rest of your potato, but the skin is where most of a spud’s nutrients are stored, so that’s a shame.
Also known as corky scab, let’s see what we can learn about this disease and how to prevent it.
The powdery scab disease
Powdery scab is caused by one-celled creatures known as Cercozoa. They are not bacteria, fungi, or viruses. Instead, they are parasitic amoebas. Specifically, it is Spongospora subterranea that causes powdery scab. These microscopic critters exist around the world. Tomatoes, nasturtiums, and other members of the nightshade family can also become infected with powdery scab. Once infected, plants are more susceptible to other diseases, such as potato mop-top and potato scab. Powdery scab spores can remain viable in the soil for up to 10 years.
Powdery scab symptoms
Small, purple lesions that look like pimples first form on a potato’s skin. Those lesions grow bigger and bigger and then they rupture, sending spores in all directions. Those spores are white. To the naked eye, these spore clusters look like scabs. You may also see galls on infected roots, leaf wilting, or discolored stems.
How to prevent powdery scab
The easiest way to prevent powdery scab in your potato patch is by planting only certified disease-free eye potatoes. I know it’s tempting to use spuds and other vegetable starts from the grocery store. They’re certainly convenient, and you already have them, but they can bring a world of hurt to your garden. Produce bought at grocery stores is certified safe to eat, but it can still carry soil-borne diseases that may linger in your soil for many years. If you are growing in containers, this is less of a problem. If a disease appears in that case, you can toss the soil in the trash and start over. Hopefully, you catch it before spores have been released. Other practices that will help prevent powdery scab include:
Infected potatoes aren’t the only way powdery scab can enter your garden. To prevent this disease, you need to monitor these other potential pathways:
I’m a big proponent of buying used garden gear from yard sales and thrift stores, but you have to wash everything thoroughly before using it. And always put new plants into quarantine.
Chemical controls are not effective against powdery scab.
Where you put your plants has a big impact on how well they grow.
Plants growing in a suitable environment are less likely to succumb to pest or disease problems, they tend to produce more and better-tasting crops, and they require less effort on your part. Let’s look at the conditions of the site selection decision.
What is your microclimate?
Microclimates are the localized conditions of temperature, drainage patterns, moisture, sunlight, wind, soil, and other factors that make one site more suitable to some plants than others. If you are growing plants indoors, your home is your microclimate. In fact, each room will have a unique microclimate. The often dark, moist bathroom environment is significantly different from a sunny living room with lots of activity (airflow). You get the idea.
When growing plants outside, your microclimate will be a variation on whichever USDA Hardiness Zone you live in. Your outdoor space will probably have multiple microclimates unless you are like me, growing on a single balcony.
Taking the long view
It may be difficult for you to picture what your garden will look like at the end of the growing season, or a few years down the road. It’s a matter of taking lots of baby steps to a long-term goal. Drawing pictures and creating a sun map can help.
When selecting the best site for a plant, you need to keep its mature size in mind, as well as its environmental needs. Those environmental needs include healthy soil with the proper pH and the proper sun exposure.
The right sort of sunlight
Very few plants can thrive in an interior bathroom with no window. It’s just too dark most of the time. I’m sure there are exceptions [and I would love to hear about them in the comments]. But the amount of light a plant receives is one of the most limiting factors in its growth. Little light usually means little growth, especially in the world of fruits and vegetables.
Sun exposure can be full sun, partial sun, partial shade, or full shade. Those tomatoes, eggplants, and most herbs need 8-10 hours of full sunlight each day. While beans, garlic, and Swiss chard can get by with 3-6 hours of partial sun, and spinach and cabbage can be productive in partial shade. Read those seed packets to see what sort of sunlight your plants need to grow well.
Distance to water
Your plants will need watering. The more convenient that task is, the more likely it is to be done regularly. Back in the day, gardeners had to collect water in heavy clay pots and carry it to their crops, usually on their heads. Ouch! That thought sure makes me grateful for garden hoses. But, here in my apartment, I don’t have a hose. I have a watering can and significantly fewer plants than I used to have. If you have a big yard, you’ll want to position your plants in such a way that watering is made easy. You can simplify your watering task by placing plants in hydrozones. Hydrozoning refers to putting plants with similar water needs close to each other. But not too closely.
Each plant needs to go somewhere. In my post on plant spacing, we saw that the distance between plants impacts how healthy and productive they are. Read those seed packets and do your homework before deciding on a site for each plant.
My recent post on plant spacing and an earlier post on rooting depth got me thinking about what I should plant in my two strawberry pots, now that I’m settling into my Seattle apartment.
What are strawberry pots?
Also known as strawberry jars, these containers are usually upright, porous clay urns with cup-shaped pockets on the sides. You can also find strawberry pots made from plastic, resin, fiberglass, and cement. But I would avoid those last two for edible plants. Whatever material it’s made of, your strawberry pot must have a drainage hole.
What grows in strawberry pots?
Traditionally, strawberry pots are used to grow, well, strawberries. Each cup is given its own strawberry plant, and one goes in the opening on top. You can find countless online images of lush leafy growth and big red, juicy strawberries cascading from strawberry pots. The pots I have seen used for strawberries haven’t looked anything like that. Instead, they tended to be more spindly and less productive than the photos suggested. That may have just been the ones I saw, or it may have been the fact that strawberry roots, given the opportunity, can dig down as much as three feet.
I have successfully grown basil, chives, cilantro, lettuces, oregano, parsley, saffron crocus, and summer savory in my strawberry pots, even though they aren’t very big. My pots are 14” high and 10” wide, and the other is only 10” high and 10” wide.
If you want plants that look nice and require very little care for your strawberry pot, nothing beats succulents. They are colorful, durable, and can often survive winter temperatures with just a little protection, depending on where you live, of course.
Watering a strawberry pot
One of the downsides to strawberry pots is irrigation problems. Strawberry pots tend to dry out quickly. Also, their design makes it such that the plants at the top tend to get all the good water. The plants at the bottom often end up soggy, and the ones in the middle always seem to be on the verge of water stress. But I recently learned of an easy way to correct that problem, with a watering column.
A watering column is a tube inserted down the middle of the pot. It has several holes in it, allowing water to disperse more evenly. To make your own watering column, get a piece of PVC pipe that is slightly shorter than your pot and drill a bunch of random ¼” holes in the pipe a couple of inches apart in it.
After adding a few inches of potting mix to your pot, stand the pipe in the center. You might want to stuff a paper towel into the top of your watering column to keep the soil out while you continue adding soil. As you come to each side cup, add a plant of your choice and continue adding soil until the strawberry pot is full. Now, you can add water through the watering column. You may need to fill the watering column more than once, especially the first time, and all of the pot’s residents should get the water they need.
What’s growing in your strawberry pot?
To grow optimally, most plants need plenty of room for roots to grow down, stalks to grow up, and stems to grow side-to-side. Being planted too close to a wall, fence, or other plants can reduce airflow and sun exposure and increase rubbing damage, insect spread, and disease transfer.
Spacing plants properly is one of the easiest ways to ensure maximum growth and delicious harvests while reducing pest and disease problems. Too many plants growing too closely together makes it difficult for any of them to grow properly. It ranks right up there with seed planting depth when it comes to plant health.
How much space does my plant need?
How much space is needed depends on the type of plant. Pole bean seeds can be planted a hand’s distance apart and thrive as long as they have something to climb. If your cabbages are crammed too close together, you may never get decent heads. Seed packets are a great place to start for information on plant spacing, but there’s more to it than what meets the eye.
What about the roots?
It’s easy to see how big a mature plant is when you look at it, but what about the root system? How big is it? How much room does it need? How close can it be to its neighbors? You may already know that some root systems spread out while others have taproots that tend to go straight down, but the answers may surprise you.
UPDATE: Thanks to information from Jim on pepper growing research, I have learned that peppers can actually be grown 10-12" apart, rather than the 18" listed above.
Putting several shallow-rooted plants close to each other can reduce plant health and productivity. Mixing shallow-rooted plants with deeper-rooted plants makes the most of a space.
Intensive plantings have their place
Intensive planting is also known as square foot, postage stamp, and biodynamic gardening. It refers to the following set of principles:
These guidelines are all good, and they do work. Problems occur when gardeners pick and choose which aspects of the intensive gardening program they actually use. In many cases, plants are installed too close together and gardeners still step on the beds.
Intercropping, the science-based version of companion planting, also puts plants closer together than is recommended on seed packets, but with good reason. Intercropping takes advantage of the benefits offered by different plants to make the most of garden space. The Three Sisters Method of growing corn, beans, and squash together is a good example of intercropping. Corn grows tall, pole beans climb the corn and provide nitrogen, and the broad, bristled leaves of squash plants shade the ground. You can replace the corn and squash with sunflowers and lettuces for similar results. You get the idea. Intercropping also puts trap crops, chemical warfare, and biodiversity to work for you, but that’s a different post.
The art of thinning
As seedlings grow, you may need to thin them out. Rather than pulling unwanted seedlings (or weeds) out, use scissors to snip them off at the soil level. This leaves the remaining plants with their roots undisturbed. It also protects the millions of beneficial soil microbes attached to the root systems. Those microbes will migrate to the remaining plants and help them grow.
Bottom line, if you want to get the most from your garden, plant seeds at the proper depth and transplant them with mature sizes in mind.
Spraing is the word used to describe the brown lines that appear on the inside of potatoes. Also known as corky ringspot disease (CRS), this condition interferes with potato storage. And, hey, it doesn’t look very appetizing either.
Those brown lines can be caused by one of two viral diseases: potato mop top or tobacco rattle. They can also be caused by irregular watering, mechanical injury, and calcium deficiencies. There are other causes of brown marks inside your potatoes. We’ll get to those, too.
Potato mop top
Potato mop top virus (PMTV) is spread by the powdery scab fungus (Spongospora subterranea). The two entities work together to support each other. Since the fungus can remain viable in the soil for up to 18 years, it’s a good idea to ensure proper drainage. Leaves of infected plants have odd areas of bright yellow.
Tobacco rattle virus (TRV) is spread by nematodes as they feed. Infected plants may look normal aboveground, at first. Eventually, leaf mottling and distortion may be seen. Infected tubers exhibit necrotic arcs and lines both on the surface and inside. Leaves of plants infected with TRV may have localized yellow spots with green centers. Tobacco rattle is most common in sandy soils after it rains. This disease is best prevented by applying nematicides and planting resistant varieties.
Other causes of internal browning
There are several other causes of browning on the inside of potatoes, but symptoms look a little different from spraing:
How to prevent spraing
Investing in certified pest- and disease-free seed potatoes is the best way to avoid those brown streaks. Since irregular watering can lead to several problems, including hollow heart, splitting, and spraing, water regularly. Good drainage can also help prevent these problems.
How are your potatoes growing?
When a cauliflower plant fails to produce a head, the condition is called “blind” or “blind bud”. Everything else about the plant looks perfectly normal, there is simply no head
Since cauliflower plants take time, water, and real estate to grow, the lack of head production can be very disappointing. There are several causes for blindness in cauliflower, and many of them are preventable.
How do cauliflower heads form?
When a healthy cauliflower plant grows, it starts out by producing significant numbers of large, broad leaves. In the center of all that lush growth is a small nub of a bud. That bud (apical meristem) grows into the dense head of curd we know as cauliflower, except when it doesn’t. Bud blindness can be caused by bad seed, damage, or temperature extremes.
When the growing tip of a cauliflower plant is damaged by animals, birds, disease, insects, or human collisions, a head can fail to form. Common insect pests include aphids, flea beetles, leafhoppers, and slugs and snails. Animals and birds are often attracted to these tender buds. Once they are eaten (the buds, not the birds), it’s too late. Some of these pests can be thwarted by floating row covers.
Too hot (or cold) to handle
Cauliflower heads form best when temperatures are in the 50°F to 60°F range. Temperature spikes in either direction beyond that range may damage the growing tip to the point that a head cannot form. Providing shade or shelter, as needed, can protect that tender growing tip.
You can also prevent blind bud by selecting varieties suitable to your USDA Hardiness Zone, starting plants at the proper time, and spacing plants with mature sizes in mind.
There is simply nothing that compares with a homegrown cauliflower.
Browning is not something that takes place in a sauté pan. It is a symptom of boron deficiency in cauliflower characterized by hollow stems and curds that turn brown and bitter.
How do plants use boron?
Boron (B) is a micronutrient that helps maintain plant cell walls. It helps produce and transport sugars, seeds, pollen, and flowers. And it helps metabolize nitrogen. In the world of plant food, micronutrients are only used in tiny amounts, but they are critical to plant growth. The optimal range for boron found in a soil sample is 0.1-0.5 parts per million (ppm). The only way you can determine how much boron is in your soil is with a laboratory soil test. Take my word for it, it’s the best investment you can make in your garden, next to mulching. Back to browning.
Boron deficiencies are more common in areas with frequent rainfall and acidic soil. If a lab-based soil test indicates a boron deficiency, you can apply borax to your soil. How much your soil needs will depend on how much is already there. Too much can be just as bad as not enough. If you need help figuring it out, you can always contact me. Boron-deficient heads that otherwise look normal may be saved if they are protected from sun exposure. You can do this by simply pulling leaves up and around the curds and tying them in place with a string. If the deficiency is bad, the curd will still taste bitter.
If you grow cauliflower, a soil test is a good investment.
And if you happen to have better photos that I could use, please let me know. Thanks!
Whiptail is a disorder of broccoli and cauliflower.
Growing cauliflower and broccoli takes time, space, and water. It can be frustrating to invest all that effort, only to have the heads be inedible or nonexistent. Whiptail describes the way leaves of some plants become skinny. Heads may be smaller and ugly, or not there at all. Luckily, whiptail is preventable. Read on!
Stunting and severe chlorosis of leaf edges (margins) in young plants is the first symptom of whiptail. Those leaves may ultimately turn white. As the condition worsens, leaf blades do not develop properly, even though the midrib grows as it usually would. This creates a thin, strap-like shape to the leaves. Leaves may also cup upwards. It is not uncommon for outer leaves to look perfectly normal while the rest appear to be going insane.
Instead of getting large, delicious heads, whiptail causes them to be smaller, malformed heads that taste less sweet. Or they may not grow at all. To complicate things, whiptail symptoms are similar to manganese toxicity. Manganese toxicity appears as lightened leaves (interveinal chlorosis) with dark veins, leaf crinkling and puckering, dark spots on leaves, and stubby or absent buds.
What causes whiptail?
Whiptail is caused by molybdenum deficiencies in the soil. Molybdenum is a micronutrient used by specific enzymes. These enzymes have a laundry list of valuable jobs. Most importantly, they help make nitrogen and phosphorus available to plants. Legumes and members of the cabbage family use a lot of molybdenum, relatively speaking. When molybdenum is in short supply, those enzymes can’t do their jobs.
Molybdenum deficiencies are common in acidic soils with a pH below 5.5.
Knowing what is in your soil is the first step toward preventing whiptail. The only way to really know is with an inexpensive lab-based soil test. Don’t be scared off by this. These tests cost about the same as a large bag of fertilizer, and the information they provide is invaluable. They will also tell you your soil’s pH. Once you know what’s in your soil, you can add any specific nutrients needed and work on getting rid of whatever may be present in excess.
Regularly adding organic matter to your soil will help prevent whiptail by improving soil health and adding easily accessible nutrients. If needed, adjust your soil’s pH. If your soil is too acidic, you can apply lime to “sweeten” it. Ammonium molybdate is often recommended, but it is highly toxic and can cause chemical burns. Personally, I wouldn’t want it anywhere near my edible plants. That’s just me.
So, if you see skinny leaves where they should be broad and abundant, take a closer look at what’s in your soil.
Silvering can be a symptom of disease, environmental stress, insect feeding, or mineral deficiencies, similar to bronzing.
Silvering is not the same thing as chlorosis. Chlorosis refers to leaves becoming a paler green over time, usually due to insufficient nitrogen, and eventually turning yellow. Chlorosis can ultimately lead to silvering, but silvering generally describes how some leaves become white rather than yellow. There are several causes for silvering.
Diseases that cause silvering
Silvering may occur in mosaic, a collection of viral diseases. Leaf silvering is also a symptom of, wait for it, silver leaf. Silver leaf is a fungal disease of apple, cherry, and pear. If you see whitened areas under the skin of peppers or tomatoes, it may be fruit silvering. The Phytophthora oomycete causes fruit silvering, avocado root rot, buckeye rot, and potato blight. But I digress.
Environmental stresses that cause silvering
Drought and temperature extremes can cause silvering. Chemical overspray and pollution can also cause leaves to turn silver. This is common among tomatoes and peppers. Also known as chimera or head silvering, environmental stress can turn leaves grayish-green and smaller than normal. You may also see blisters on the leaves and pale streaks on the stems. When this occurs, flowers are usually sterile. Any fruit that grows will have grayish-green streaks and be less flavorful. If you see white patches on fruit, it is probably sunscald.
Silvering due to insect feeding
Sap-sucking insects can cause leaf silvering. The most common causes of leaf stippling or silvering include feeding by:
Silvering due to nutrient deficiency
Potassium deficiencies can cause leaf silvering. In this case, you will see upward leaf curling. Manganese deficiencies can cause leaf silvering, premature leaf drop, smaller-than-normal leaves and seeds, and weak roots and stems. An inexpensive lab-based soil test can help determine if this is the problem.
Silver in the garden isn’t always a bad thing. Silver plants can add a nice color contrast to potted plants and landscapes, too. These plants usually prefer full sun. They often get their silver appearance from a coating of white trichomes that look like fur. Most white and silver plants are ornamentals, such as:
But there are few edible silver plants:
Radicchio is a type of leaf chicory (Cichorium intybus). Its white-veined red leaves make it a striking addition of flavor and complexity to salads and other dishes. You can always tame its bitterness by roasting or grilling.
A close cousin to Belgian endive and sugarloaf, radicchio is also known as Italian chicory. This cold weather plant is a popular ingredient in many Italian dishes, from risotto and strudel to soups and tapenades. It’s so popular, in fact, that each region of Italy has its own type of radicchio. Each varietal is protected legally, like Le Puy lentils, Bordeaux wine, and Champagne. The radicchio chicory we get in the U.S. is usually the Chioggia variety.
Chioggia radicchio looks similar to red cabbage. It will store well in your refrigerator for weeks, though using it sooner is better than later. Treviso radicchio is more elongated with more white than red, and it looks similar to large endive.
Tardivo is a curled-leaf version of Treviso coaxed into its unique shape through careful cutting, blanching, and regrowing methods similar to Belgian endive. Castelfranco radicchio has pale green leaves and red freckles. It is sweeter than other radicchios. Other varietals include Palla Rossa and Rossa di Verona.
How to grow radicchio
Like other chicories, radicchio is a perennial plant. You can cut heads off the top indefinitely. The quality of the harvests is said to deteriorate over the years, so you may want to add new seeds every so often. You can also use succession planting for an ongoing harvest.
Radicchio prefers loose, nutrient-rich soil with good drainage. Regular watering reduces bitterness. Radicchio can be grown in USDA Hardiness Zones 4-10, though it prefers zones 8 and above. Seeds should be planted ¼” deep and thinned to 12” apart.
When you start your radicchio plants depends on where you live. In warmer climates, radicchio is a cool-season crop planted twice each year. Start one batch in January or February for an early summer crop. Plant again in July or August for an early winter crop. This gives the seeds time to get established before the weather turns too hot or cold. Chicory grown in areas with scorching summers tends to bolt, making the leaves taste more bitter. These plants can tolerate temperatures in the low 20s (°F). Light frost makes them sweeter. You can protect them from lower temperatures with row covers, cold frames, and hoophouses.
Radicchio pests and diseases
Very few problems will occur for your radicchios, as long as they are well-fed and watered. All members of the chicory family are susceptible to the following: anthracnose, bacterial soft rot, bottom rot, damping-off disease, downy mildews, fusarium wilt, septoria blight, and white mold. Aphids, cabbage loopers, darkling beetles, flea beetles, leaf miners, thrips, and slugs and snails may feed on your radicchio plants. You’ll want to avoid overhead watering, as the leaves are prone to rotting. And brassica collars can thwart some of those pests.
Ancient folklore warned that eating too much radicchio would lead to dimming vision. Science has not found cause for those claims. Eating radicchio and other chicories will help combat intestinal worms, however. If you are a farm animal, that is.
Now you know.
Winter squash isn’t something you grow in winter.
Instead, the terms winter squash and summer squash refer to when these crops are eaten, not when they are grown. Thin-skinned summer squashes, such as zucchini and yellow crookneck, are best eaten fresh, while immature. Sturdy, thick-skinned winter squashes can be stored for several months. Their hard, protective rinds are generally removed before eating and their seeds are delicious when roasted with a little oil and salt. Acorn, butternut, Hubbard, and turban squashes are all winter varieties. So are pumpkins.
Did you know that most canned pumpkin puree is actually squash? Pumpkins and other winter squash share enough characteristics as to be indistinguishable according to the FDA. Huh. How about that? No matter. Growing pumpkins and other winter squash can be very rewarding and easier than you may think.
How to grow winter squash
Winter squash grows best in full sun, but it seems to perform just as well in partial shade in areas with especially hot summers. (I have successfully grown butternuts under a nectarine tree and they both seemed happy about it.)
After temperatures have reached a steady 70°F, winter squash seeds are planted in hills. Each hill gets 4-5 seeds. If you have room for multiple hills, they should be spaced 4'-8' apart, depending on the type of squash being grown. After your seedlings are 2"-3" tall, select the best two or three for each hill and snip the rejects off at soil level. If you are growing winter squash in rows, seeds should be planted 6"-12" apart in rows that are 6'-10' apart, thinning seedlings to one plant every 18"-36". These plants can take up a lot of space, given the opportunity. You can also redirect them along walkways, lawns, or fences. Depending on the size of the fruit, you may need to provide hammocks as support.
It takes a lot of water to make a winter squash. During fruit set, each plant should receive approximately 1" of water per week. (One inch of water is equal to 0.623 gallons per square foot.) Since most winter squashes are shallow-rooted, it is not a good idea to disturb the soil. Butternut squashes are something of an exception, with deeper root systems that help them through scorching summers and drought. Keep your squash watered and mulched and you are sure to get an abundant crop.
Winter squash problems
Winter squashes are members of the melon family. Also known as cucurbits, all members of the melon family are susceptible to several diseases and disorders:
Many of these problems can be prevented by avoiding overhead watering and managing disease-carrying aphids.
Along with aphids, the following pests may appear in your winter squash patch:
Winter squash plants need to be watered regularly to prevent blossom end rot, bitter fruit, and blossom drop.
If all that weren’t enough, molybdenum deficiencies can cause a condition known as yellows. Yellows eliminates squash fruit set and generally kills the plant. Sporadic watering and insufficient calcium can also cause blossom end rot. Soil tests from a reputable lab are the best way to learn what’s in your soil.
You might think, with all these threats to your winter squash crop, you might not get anything for all of your efforts. The truth is, winter squash plants are very productive, much like their summery cousin the zucchini plant. Despite all those potential problems, you will probably end up with plenty of winter squashes to share with friends and neighbors.
Harvesting winter squash
Winter squash are ready to harvest when the rind is firm and the stem is shriveled. You can leave them to cure on the vine or cut them off and store them in a cool, dry location with good airflow. Garages work nicely. After your winter squash has cured, it will remain edible for several months.
You can grow a surprising amount of food in your own yard. Ask me how!
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