Sometimes plants grow in ways you might not expect.

Galls are like warts or tumors in the plant world.

If you cut a gall open, you will see distinctly arranged vascular tissues, depending on the cause of the gall, and an enlarged cambium layer. These distortions interfere with the flow of water and nutrients, leading to wilting and stunting. Or, you may see a large, open area, perfect for use as a larval nursery, with no noticeable impact on the host plant.


​Insect, mite, and nematode galls

When insects invade a plant, they build galls. These galls can act as food or shelter for insects. They are not the same as the plant-produced domatia (tiny apartments) found in some thorns for beneficial insects. Insects inject chemicals (pseudo plant hormones) into host plants, triggering gall formation. Often, eggs are laid in these galls, providing developing larvae with food and protection. Gall wasps, sawflies, gall flies, scale insects, some aphid species, weevils, psyllids, and gall midges can all cause insect galls, but it is nearly always gall wasps or gall midges.


Nematodes are microscopic round soil worms that can cause small galls on roots. Root knot nematodes are one such pest. These galls are made up entirely of plant tissue, unlike fungal and bacterial galls, which incorporate fungal or bacterial tissues, respectively. Insect galls may also house interlopers, technically called inquilines.


Fungal galls

When a fungus infects a plant, it grows alongside plant cells, creating swollen areas that can develop into galls. Several varieties of rust can cause galls to form. When these galls form on conifers, as in the case of cedar apple rust, they look like glutinous fingers called telial horns.

The truth about nuts may surprise you.


While you probably already know that peanuts are not nuts (they’re legumes), many of the other foods you have come to know as nuts are not true nuts at all. Let’s begin by learning the botanical definition of nuts.

True nuts are hard-shelled, inedible pods that hold both the fruit and the seed of a plant. These pods do not open of their own accord, which means they are indehiscent. The pod, or shell, of a nut is made from the ovary wall, which hardens over time. Hazelnuts, chestnuts, and acorns are true nuts. So are kola nuts, which gives “cola” soft drinks their signature flavor.

A nut is not a nut when it is a fruit seed. Fruit seeds can be angiosperm, drupe, or gymnosperm seeds:

• Gymnosperm seeds, such as pine nuts and ginkgo nuts, are not true nuts.
• Angiosperm, or flowering plants that produce seeds within a carpel, include macadamia nuts, Brazil nuts, peanuts, and soybeans.
• Drupes, such as peaches and cherries, are a type of angiosperm which have hard-shelled pods that hold a seed, but their fruit is on the outside. Almonds, cashews, pecans, pistachios, walnuts, coffee beans, and coconuts are all drupes.

These not-nut nuts are commonly referred to as culinary nuts.

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[Did you know that cashews are the seeds of an accessory fruit, which means they share characteristics with strawberries and poison ivy. Isn’t botany amazing?]

Of course, you can call any of these delicious morsels "nuts" whenever you want to. True nut or culinary nut, many of these yummy snacks find their way into our gardens and foodscapes. Which ones are you growing?

Bronzing your baby's shoes is one thing; bronzing in the garden indicates a problem.

What is bronzing?

Bronzing refers to how some leaves or fruit turn purplish or bronze-colored due to mineral imbalances, pest feeding, chemicals, environmental conditions, or disease. Bronzed leaves are often smaller, and damaged areas cannot perform photosynthesis. Bronzing damage may look similar to sunburn damage, except that sunburned leaves tend to turn gray rather than bronze. Bronzed fruit has a dry, rough texture.

Mineral imbalances
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Too much or too little of certain minerals can cause bronzing. Regularly adding organic material to your garden soil helps minimize mineral imbalances. But it’s still a good idea to know what to look for when scouting your foodscape:

Chlorine deficiency – More likely in sandy soils, symptoms include bronzing, stunting, necrosis, chlorosis, and wilting.

Copper deficiency – Copper deficiencies are rare. When they occur, they make trees look more like shrubs than trees. Bronzing, shoot, twig and needle dieback, and witches’ broom are common symptoms.

Iron toxicity – Iron toxicity often appears as bronzing and reddish spots. These symptoms are from iron oxidizing the chlorophyll used in photosynthesis. In areas with heavy clay soil, insufficient iron is more likely.

[Did you know that rice farmers rate their plant varieties using leaf bronzing scores (LBS)? They rank rice varieties according to their ability to tolerate excessive iron in the soil.]

Manganese deficiency – Manganese is an immobile nutrient, so deficiencies are seen in younger leaves first. Manganese deficiencies look very similar to iron (Fe), magnesium (Mg), and nitrogen (N) deficiencies, with interveinal chlorosis and bronzing. Brown specks may also be visible.

Sodium toxicity – Too much sodium can cause severe chlorosis, bronzing, and leaf drop. Stunting and other water stress symptoms are also common.

Zinc deficiency – Rare in most areas, zinc deficiencies appear as twig dieback (necrosis), yellowing (chlorosis), and leaf bronzing, often caused by too much phosphorus in the soil. Zinc deficiencies are more common in container plants.


Pest feeding

As pests feed, leaf and fruit bronzing may occur. Most of these pests are sap-suckers:

• Mites can cause leaf stippling and bronzing. Fruit can also take on a russet, bronzed appearance.
• Nematode feeding may cause bronzing and stunted growth of boxwood.
• Thrips may cause bronzing and downward leaf curling of lettuce, strawberries, blueberries, boxwood, and many other plants.
• Aphids, scale insects, and whiteflies may also cause bronzing.

Chemical damage

Damage can occur when herbicides, pesticides, and fungicides are incorrectly applied. Also, the wind can carry herbicides and other chemicals from neighboring gardens and yards that may cause leaf bronzing. Bronzing, necrosis, interveinal chlorosis, desiccation, and distorted growth may indicate chemical misuse or overspray.


Environmental conditions

Air pollution often causes high ozone (O3) levels in the atmosphere. Ozone, combined with high temperatures and bright sunlight, can cause purple-brown discoloration, or bronzing, on the upper surface of leaves. Bean plants are especially vulnerable to air pollution.


Disease

Many plant diseases include bronzing as a symptom. These include spotted tomato wilt (carried by thrips), phomopsis stem canker in sunflowers, alfalfa mosaic, cotton root rot, and blueberry bronze leaf curl.


Use bronzing as a clue when you walk through your garden. The brownish or purplish discoloration of bronzing is a clear sign that something is amiss.

There’s a lot more to wind than meets the eye.


You may not see it, but gentle breezes and wailing typhoons carry insect pheromones, fungal spores, viruses, and bacteria. Gentle breezes help plants develop stronger stems, and gale-force winds can rip trees from the ground.


Beneficial winds

Seedling development is a function of sunlight, moisture, temperature, and wind. Being blown around stimulates the stem to be stronger. Botanists call this action thigmomorphogenesis. Plants grown in greenhouses, without any wind, are gently knocked around by a machine that helps prevent the plants from becoming too tall and spindly.


Note: While most pollen is too sticky to be affected by wind, wind is the primary mechanism for pollination of corn plants.

Wind damage

Wind dries plants out. Plants exposed to a lot of wind need more water than their protected brethren. Wind can also speed up erosion. Ground covers and mulch reduce that erosion. During heavy winds, you may want to move containerized plants next to a fence or wall to prevent breakage. 


Protect tall plants against wind damage with stakes, tree supports, and tomato cages. Wind damage can be in the form of branches flailing around and tearing holes in leaves and branches rubbing together. Wind damage provides pathogens with a way in. And hot summer winds can lead to blossom drop and fruit set failure.


Wind wounds

Strong winds can rip heavily laden branches or overly large limbs from a tree, leaving jagged wounds. You can help these trees recover quickly by cutting the tear to make it a flat surface, close to the trunk, but not too close. Do not cut into the branch collar. And you do not need to paint the wound. Instead, allow the tree to protect itself. It will grow a callus over the area. You may, later on, need to provide the callus with sunburn protection.


Diseases on the breezes

Disease-causing pathogens are usually microscopic. As such, they can catch a free ride on every breeze that blows through. [I wonder if that would make it a case of phoresy…] In any case, several diseases can arrive in your garden in the wind. Gray mold (Botrytis cinerea) is always present. That is why rotting fruit gets that gray fuzz so quickly. It’s everywhere. 


Mummy berry spores blow into your garden on the wind. So do chemical oversprays. The chances of ringspot on Brussels sprout skyrockets after a windy day, and citrus blast often occurs right after periods of wind-driven rain. You can reduce the likelihood of citrus blast by providing citrus trees with some wind protection.


Wind protection

Wind protection can take many forms. It may be a fence, a hedge, or a row cover.. You can protect plants from wind by installing them close to your house. Pineapple guava, mature blueberry bushes, and many fruit and nut trees can provide a windbreak. Portable cold frames can protect smaller plants against cold winter winds. 


When spring comes around, wind can mess up a plant trying to get established in a new location (ecesis). The wind is one of the main reasons for taking the time to harden off plants started in protected areas. And when you start planting those tiny seeds, such as lettuce, you can often lose most of your crop to the wind. They simply blow away. [You may want to check your neighbor’s yard for all that lettuce and endive you planted last year…] And all those delicate seedlings that emerge can be protected from the wind with a moistened layer of vermiculite. Or, you can cover them with a plastic gallon jug (cloche) with the bottom cut out. Just be sure to bury the edges or weigh down the jug enough to prevent it from blowing away, too!

Calyx as flower part
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Calyx is another word for sepal. Sepals are the green petals at the base of a flower that are modified leaves. The calyx is also the green leafy area at the top of a strawberry fruit. Sometimes, the calyx is the same color as its flower. In most cases, once a plant is done with the flower, the calyx is discarded. Tomatillo plants retain the calyx as a thorny protection. In other cases, the calyx begins to grow in earnest after the flower is fertilized, creating a protective bladder-like enclosure. The sepals of Hibiscus sabdariffa turn into an edible accessory fruit.

Calyx as hiding place

Many fungi, such as botrytis cinema, love to hide under the calyx, waiting for a splash of rain or irrigation water to start breeding gray mold and feeding on your berries and other garden produce. Sometimes the calyx falls victim to the very pathogens it protects, along with the fruit, as in the case of stem-end rot. In some cases, such as calyx blight, only the calyx becomes infected and the fruit remains fine.


​How many different types of calyx are in your garden?

Epinasty refers to how leaves and stems turn downward when their tops grow faster than their bottoms.


While many plants move to follow the sun's path each day (phototropism), sometimes plant movements are more random. These are called nastic movements. Epinasty is a nastic movement.

There are vegetables that we call fruits, nuts that are fruits, and fruits that are not fruits at all! Before we get started, let’s look at why plants go to all the trouble to produce fruit in the first place.


How fruit benefits a plant
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In the world of plants, reproduction is the name of the game. Characteristics that evolve to promote the likelihood of a plant surviving are passed on to the next generation. Fruit is one of those characteristics. Creating fruit takes a lot of energy from a plant. But the fruit we eat has evolved to protect, disperse, and feed the seeds within. As the fruit ripens and falls, the fruit provides protection and nutrients. Fruit also encourages birds, animals, and people to spread seeds farther than the plant could do alone.

Fruit specs

For something to be a botanical fruit, it must be the fertilized ovary of a flowering plant (angiosperm). After pollination and fertilization occur, two new structures are produced: seeds (fertilized ovules) and pericarp (thickened ovary walls). There are three different types of pericarp tissue: exocarp (outer skin), mesocarp (flesh), and endocarp (inner layer). The dominant pericarp tissue can become hard, as with nuts, or fleshy, as we see in peaches and avocados. In some cases, we eat the pericarp. In others, we eat the seed. When we eat the pericarp, we call it a fruit. Sometimes.


Fruit classification

Like most things in life, the more we learn, the less simple anything is. Fruit is no exception. Fruits can be simple, multiple, or aggregate. Rather than going too far down that rabbit hole, let me summarize by saying simple fruits, such as apples and tomatoes, develop from a single ovary. Pineapples and figs are multiple fruits, which form when separate flowers cluster together. Aggregate fruits, such as raspberries and blackberries, are clusters of multiple ovaries from the same flower. Make sense? But wait! There's more! To start, simple fruits are also classified as either dry or fleshy.

Accessory fruits and non-fruit fruits

There are also accessory fruits, which are made not just from the ovary, but also from nearby tissues. Common accessory fruits include strawberries, rose hips, apples, and pears. We may as well run the gamut with this one. Rhubarb is considered a fruit, but we only eat the stems, which are technically vegetables.


Getting the best fruits from your garden

Healthy plants produce bigger fruit. Keep your plants healthy with regular inspections for pests and diseases, appropriate watering and feeding, regular pruning, and disposing of mummies as soon as they are seen.


As your fruit starts to ripen, you can make it sweeter by reducing irrigation.

How to transplant seedlings

For many vegetable crops, you can transplant seedlings with the first leaves (cotyledons) below the soil line. Very often, these meristem tissues will transform into root tissues, adding nutrients and vitality to your plants. Once your seedlings are a couple of inches tall, you should prepare their new home, making sure that the soil is loose. The Bay Area’s heavy clay can form an impenetrable barrier to new roots if it is left smooth from a trowel or shovel. Be sure to rough up the edges of the planting hole. Then, follow these steps to successfully transplant your seedlings:

1. Place your hand over the container, with the plant between your fingers.
2. Gently turn the pot on its side or upside down, tapping the bottom with your other hand to knock the soil loose.
3. Cup your first hand to hold onto as much of the soil as possible.
4. Examine the roots and spread them out if they have started wrapping around themselves.
5. Slowly turn your hand, allowing the root system to roll into the prepared hole.
6. Ensure that all roots are covered with soil. If peat pots were used, make sure all of the peat is covered, as well.
7. Resist the urge to tamp down the soil. While big air pockets can dry out roots, pushing down compacts the soil and damages delicate root hairs. Instead, use water and gravity to get rid of those large air pockets. This is called mudding in.
8. Water thoroughly.

Caring for new transplants

New transplants should be treated gently for a few days. To help a young seedling thrive in its new environment (ecesis), be sure to:
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• Harden off seedlings before transplanting.
• Water regularly, allowing the soil to mostly dry out between waterings.
• Do not use insecticidal soap or other treatments right away.
• You can feed fish emulsion or phosphorous to your transplanted seedlings a few days after their ordeal.
• Protect seedlings against cutworm damage by inserting a paperboard ring a couple of inches into the soil.
• Provide wind protection by cutting the bottom out of large plastic jugs and placing them over vulnerable plants.
• If your transplants are infected with anthracnose, they can be removed from the soil, dipped in fungicide and then replanted.
• Wilting and leaf rolling are common signs of transplant shock and often occur when plants are transplanted too early in their development.

Be sure to use plant markers when transplanting. This will help you recall where everything is!

Chilling hours are the accumulated periods of cold temperatures that allow many fruit and nut trees and shrubs to provide us with their bounty each year.


We are all familiar with the buds and leaves of spring, the prolific growth of summer, and the harvest of autumn, but fruit and nut trees and shrubs (and strawberries!) are working through winter, too. Colder winter temperatures are part of a deciduous tree’s natural lifecycle. In preparation to survive potentially freezing temperatures, many fruiting trees and shrubs produce a hormone that initiates a state of dormancy.


What are chill hours?

Just as many seeds require vernalization (a period of cold temperatures) to germinate, many fruit trees have the same need for hours between 32°F and 45°F each winter, called its chilling requirement. In this temperature range, the growth-inhibiting hormone responsible for dormancy begins to break down, allowing trees and shrubs to produce buds that ultimately become the leaves and flowers of spring. Fruiting trees and shrubs that do not receive enough chilling hours in a year will generate fruit and leaves erratically. Any fruit produced will be lower in both quantity and quality. Also, insufficient chilling hours can extend bloom time, making delicate buds and flowers vulnerable to diseases like fireblight and brown rot.


How are chilling hours calculated?

There are different models used to calculate chilling hours, but they all take the same basic information into account:

• Chilling does not occur below 32°F.
• The ideal range for chilling occurs between 32°F and 45°F.
• Temperatures above 60°F can reverse the number of accumulated chilling hours.
• Fall and winter chilling hours are more effective than spring hours.

The Utah model provides chilling hours, while the Dynamic model provides chilling portions. Whichever model you use will give you a better idea of the best varieties for your microclimate.


How many chill hours do my trees need?

Different species need varying amounts of accumulated chill hours. Within each species, each variety has its own needs, as well. For example, northern varieties of blueberries have chilling requirements of 800 to 1,000 chilling hours, while southern varieties may only need 150 to 200 chilling hours.


Your local chilling hour station

Universities work with the USDA to provide valuable information to farmers and orchardists. You can access this information to learn the cumulative chilling hours in your area. The accuracy of this information will depend on where you live and how far you are from the nearest recording station. Click on the county and town closest to you for historical averages or current season figures for hours below 45°F and those between 32°F and 45°F.


Almonds are a staple crop in California. Part of the reason is most almond varieties only need 200 to 300 chill hours. Northern California receives an average of 800 to 1,500 chill hours, while southern California only gets 100 to 400 chilling hours.


Ultimately, your fruit and nut crop will depend on pollination rates, weather, plant age, soil nutrition and structure, irrigation, and chilling hours. You can get the most out of your fruit and nut trees and shrubs by selecting varieties best suited to your microclimate and the average number of chilling hours each year.

Two plants couldn’t be more different than poinsettias and miniature pine trees, and their care is equally diverse. In each case, if these plants are simply set on a countertop and watered occasionally, they will probably never make it to the end of January. Amaryllis plants are often watered to death. Being bulbs, your holiday Amaryllis can last for several years, given the proper care.


Understanding what these popular holiday gifts need to stay healthy can transform them from short-lived hostess tokens to durable members of your garden, landscape, or home interior.


​Poinsettias
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Poinsettias (Euphorbia pulcherrima) are fascinating plants. The bright red blooms we see are bracts or modified leaves. The plant itself is a tree that can reach 13 feet in height! The flowers of poinsettia plants are tiny structures hidden away in pseudo flowers called cyathia. Native to Mexico, poinsettia plants need 12 hours of darkness for at least five days in a row to turn from green to red, in a process called photoperiodism. The slightest exposure to sunlight, street lights, headlights, or table lamps will interfere with this process. Poinsettias need strong morning sunlight and afternoon shade to be healthy. They can be grown outdoors, in warmer regions, as long as they are protected from frost.


Commercially grown poinsettias are infected with a phytoplasma (bacteria) that causes the plant to produce abundant lateral buds, which make the plant grow in a more bushy structure. Poinsettias left on their own have a more open, spindly growth. Poinsettias are susceptible to certain fungal and bacterial diseases, including leaf spot, stem rot, crown gall, anthracnose, blight, black rot, dieback, gray mold, powdery mildew, rust, scab, mosaic, and root-knot nematodes. These tendencies indicate the importance of allowing plants to dry out between waterings and providing good drainage. The University of Vermont Extension provides an excellent way to remember how to care for your poinsettias:

• New Year’s Day - feed with all-purpose houseplant fertilizer.
• Valentine’s Day - check for whiteflies; trim back to a height of 5 inches.
• St. Patrick’s Day - remove dry and faded leaves; add fresh potting soil.
• Memorial Day - cut branches back 2 - 3 inches; repot into a larger container using fresh potting soil.
• Father’s Day - move the plant outside to a location with indirect light.
• Fourth of July - trim again; move into full sunlight; water and feed, as needed.
• Labor Day - rinse plant off and move it indoors; reduce feeding as new growth appears.
• Autumnal Equinox - put plants in uninterrupted darkness for 13 hours and in bright light for 11 hours each day; nighttime temperatures of 60 degrees F are ideal.
• Thanksgiving - reduce water and feeding; place in a bright sunny window, rotating for full coverage.
• Christmas - enjoy and repeat!

As a member of the spurge family, poinsettias contain latex, which can be an irritant. Contrary to popular belief, poinsettias are not poisonous.

If you slice into a stalk of celery, you will be able to see vascular bundles that carry water, nutrients and hormones throughout the plant. These vascular bundles, or veins, are made up of the xylem and phloem. ​

The xylem mostly carries water. Xylem is Greek for wood, so an easy way to remember the word meaning is to think “water wood”. The xylem also carries some mineral salts, but that is mostly the job of the phloem. Generally, the xylem is found closer to the center of a stem, while the phloem is closer to the outer edge.


The most interesting thing about the xylem is that it pulls water upward from the ground, against gravity. If you’ve ever picked up a bucket full of water, you know this isn’t always easy. There is some debate about how this actually occurs, but most botanists agree that it has a lot to do with surface tension.


Water molecules like to stick together. As a plant breaths, evapotranspiration occurs, reducing the amount of water in the leaves and stem. The water in the ground in then pulled upward by the water in the above ground portion of the plant. The structure of the xylem helps support the water molecules as they are drawn up. 


Xylem vessels are actually made up of elongated cells that are dead. Weird, right? These cells are arranged end to end, with little openings between each cell. There are secondary xylem cells that contain lignin. Lignin is found in cell walls and it is what holds plants upright.

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Diseases of the xylem include Fusarium wilt, root rot, damping off, and tomato spotted wilt.


Children's activity: This is crazy easy and the kids seem to really enjoy it. Simply take several celery stalks and place them in separate cups or glasses. To each cup, add some water and a few drops of a specific food coloring. As the stalks pull the water up, they bring the dye too, and the color changes can be striking. (It works faster if you trim the base of each stalk to create fresh openings for the vascular tissue.)

 Too much of a good thing can be a bad thing.


And this is especially true when it comes to water in the soil. Over-watering and poor drainage often result in root rot, especially in houseplants. Once root rot occurs, the plant is doomed. ​

Plants suffering from chlorosis are unable to produce chlorophyll. Since plants need chlorophyll to help them convert sunlight into energy, it’s a significant problem that warrants a closer look without delay.


If you notice chlorosis on any of your plants, consider these possible causes:

• Insufficient sunlight - Most fruits and vegetables need at least 6 to 8 hours of direct sunlight to stay healthy and productive.
• Too much water - Over-watering can make it hard for plants to breathe.
• Pest feeding - As aphids, mites, and thrips feed, they can cause leaf yellowing.
• Disease - Several diseases can cause chlorosis, including blights, mosaics, and rots.
• Soil structure - Compacted soil and soil with poor permeability can cause chlorosis.
• Soil pH - Soil that is too acidic or alkaline can cause yellowing.
• Nutrient levels - Too little iron, magnesium, or zinc, and excessive levels of other nutrients can cause chlorosis [See case in point below.]

When I first bought my home, I sent soil samples to the University of Massachusetts Extension lab. [I think over-the-counter soil tests are a waste of money.] For the price of a bag of fertilizer, I learned exactly what was (and wasn't) in my soil. 


My soil test results told me that my soil had a superabundance of every nutrient known to humanity except iron. Since plants use iron to process nearly every other nutrient, the previous owner kept adding more fertilizer whenever her plants started yellowing. As a result, the soil had too many nutrients, interfering with the delicate chemical dance between microorganisms, plant roots, water, and nutrients.
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I sprayed my plants with liquid iron and applied ammonium sulfate. Over a few years, I was able to bring the excessive nutrient levels down a bit (which is harder than you might expect) and iron levels up. As a result, chlorosis was less common, my plants were healthier, and I saved money on fertilizer that I didn't need.


As soon as you correct the problem causing chlorosis, your plant's little energy factory will kick right in. Everything should start greening up pretty quickly.

You might be surprised to learn that your plants can get sunburned just as you can. Well, it is a little different, but too much sun can be deadly either way.

Damaged bark blisters and cracks, exposing internal tissue to pests and disease. 

Selecting plant varieties suited to your microclimate and placing them well are good ways to avoid sunburn and sunscald. Properly irrigated plants are less likely to be sunburned.


Be sure to water your plants thoroughly this summer (especially on July 4th) to help protect against sunburn, sunscald, and bottle rockets.