Mummy berry is not a seasonal breakfast cereal. Instead, it is a fungal disease of blueberries.
This particular fungal disease is caused by the Monilinia vaccinii-corymbosi fungus. It is nearly always present in the soil, but a cool, wet spring can set the stage for serious losses.
Symptoms of mummy berry
A healthy summer blueberry bush is thick with leaves and twigs, blossoms and fruit. After a cool, wet spring, however, you may notice that some of the blueberries shrivel up, turning hard and grey. Before the fruit even appears, you may see a coating of brown or blue spores on the veins of infected leaves. You may also see drooping, wilting, brownish flower clusters that are turned in on themselves, before they turn brown and die. Immature fruit falls to the ground and twig tips become blighted in a condition called ‘shoot strikes’ and die. This is mummy berry.
The mummy berry mushroom spews fungal spores into the air, which then land on all this tender new plant tissue. Spores are also carried by pollinators, such as honey bees, wind, and water. Once the fungi reach your blueberries, they need adequate moisture to continue growing. According to research from Ag Canada, the following chart tells you the likelihood of infection at different temperatures, depending on how long leaves stay wet:
If you cut open an infected green berry, you can see white fungal tissue. [Afterwards, be sure to clean your cutting tools with a household cleaner, such as Lysol. If you don’t, you will spread the infection.]
Controlling mummy berry
Once infection occurs, all you can do is removed the diseased tissue and either burn it or throw it in the trash. You can reduce the chance of mummy berry causing too much damage in your garden with these tips:
Resistant blueberry varieties
Some blueberry varieties are more resistant to mummy berry than others. According to the USDA Agricultural Research Service, low bush varieties with less than 3% mummified berries include:
However, high bush varietals are generally not recommended for warmer regions. They need more chill hours than we tend to get. There is also a cross between a southern highbush and rabbiteye blueberry, called 'Pearl River’, that is resistant to mummy berry. The ‘Berkeley’ variety seems to be the most vulnerable to mummy berry infection.
To enjoy the lush, sweet flavor of blueberries in summer, be sure to monitor your plants for signs of mummy berry!
Witches' brooms are a common sight in autumn landscapes, but there is one variety that you will want to watch out for.
Strange growths that look like witches' brooms are a symptom of plant disease or tissue damage, most commonly affecting woody plants, such as trees.
Symptoms of witches' broom
Witches' broom is easy to recognize. Where there is normally a single twig or stem, a clustered riot of shoots emerge, pointing in every direction. Stems may be twisted, discolored, or dwarfed. From a distance, it may look like a squirrel's nest, or an area of especially dense foliage. Closer inspection reveals a distinct deformity.
Causes of witches' broom
There are several conditions that can cause witches' broom. Some diseases, such as aster yellows and squash gourd mosaic can cause withes' broom. Sometimes it is a malfunction within a plant's hormone system. Auxin, a plant hormone that regulates plant cell growth, can be thwarted by a different plant hormone called cytokinen. Left to grow uncontrollably, stems grow in every direction, in every place possible. This burst of growth ends up looking something like a messy witch's broom, hence the name. Witches' broom can also be caused by bacterial plant parasites called phytoplasma. Phytoplasma were discovered in 1967 and no one has been able to recreate these pests in the laboratory. This makes studying them and developing control measures difficult. Fungi, mistletoe, mites, nematodes, and viruses may also cause this growth deformity. But sometimes deformities are not a bad thing.
The good witch
In some cases, the witches' broom that emerges is more of a dwarf version of the parent tree. Very often, that dwarf version can be removed and propagated. This is how many of our modern dwarf confers were first begun!
Bad for the kitchen garden
Witches' broom can wreck havoc in your vegetable garden. The same conditions that cause aboveground twigs to grow uncontrollably can make your carrot and other root crops inedible. There is no known cure for witches' broom and infected plants can spread the problem throughout your landscape. Your only recourse is to remove and dispose of affected plants in the trash. Do not compost them.
Preventing witches' broom
Unless you have the time to create new plant species, your plants will be healthier if you can prevent this problem in the first place. Phytoplasma catch a ride to your plants using leafhoppers, in a behavior called phoresy. Controlling leafhoppers can reduce the occurrence of witches' broom. Also, proper pruning, to remove dead and diseased branches, crop rotation, and general garden sanitation, can reduce the likelihood of witches' broom occurring.
If witches' broom occurs in your landscape, remove the affected stems several inches below the distorted area. Be sure to sanitize cutting tools afterwards with a household cleaner, such as Lysol, and dispose of the affected plant material in the trash.
Discarded limbs, scattered petals, seeds and fruits thrown to the ground - abscission!
Abscission is the intentional shedding of body parts. Some lizards do it with their tails, we do it with our teeth, and mushrooms do it to their spores. All plants use abscission as a normal part of their lifecycle, but for different reasons and in different ways.
Anatomy of abscission
The area where abscission occurs is called the separation zone, or the abscission zone. When abscission occurs, enzymes are released that breakdown the structural cellulose and the adhesive pectin within cells in the abscission zone. The timing and methods of abscission depend on the reasons behind the action.
Forms of abscission
There are four basic forms of abscission:
The abscission process
When a plant decides to get rid of a body part [How weird would that be for us? I guess it’s like having a tooth pulled. Yikes!] Anyway, the plant goes through three steps to get rid of unwanted parts: remobilization, protection, and then detachment. During remobilization, resources are pulled from the unwanted part to be used elsewhere. Then, because gaping holes aren’t good for anyone, plants use cork to seal off soon-to-be exposed areas. Detachment can occur in several ways:
Leaf, fruit, and blossom drop are not uncommon, and there are several causes that trigger detachment:
If your plants are losing body parts, see if you can use this information to determine the cause!
Scarification is not what you go looking for in a haunted house. Instead, scarification is the damage done on purpose to certain seeds to increase their chances at germination.
Scarification refers to three methods used to damage hard, protective seed coats, allowing more air and water to enter. This speeds up the germination process. Scarified seeds do not store well, so they need to be planted soon afterwards. Scarification can be done by mechanical, chemical, or thermal methods.
Plants suited to scarification
Scarification is particularly useful when planting woody legumes, lupines, nasturtiums, morning glories, lotus, moon flowers, sweet peas, birdsfoot trefoil, milkweed, or hazelnuts. Generally, it is the larger seeds that need scarification. Beans are the exception to that rule. While you can scarify bean seeds, they don’t need it to germinate.
In nature, scarification occurs when animals chew hard-coated seeds (mechanical). Passing through an animal’s digestive system also degrades a seed's natural protection (very chemical). Some plants need smoke or fire (thermal scarification) before their seeds will germinate. Also, exposure to changing weather patterns, ice or snow, will, over time trigger a seed to germinate. Sometimes, we don’t want to wait that long.
Commercial agriculture relies heavily on crops that grow and reach maturity at a consistent rate. It’s the only way to take advantage of the economies of scale provided by heavy farm equipment and large acreages. Scarification can help farmers get crops to grow uniformly by triggering seeds to germinate at the same time with these artificial forms of scarification:
Before you plant a seed, learn as much as you can about its natural life cycle. This information can help you decide if scarification is a good idea.
Just be careful not to harm the seed within (or your fingers)!
Onion maggots are the larval form of the Delia antiqua, or onion fly.
Onion maggot description
Onion flies are brownish gray versions of your average housefly, only smaller. The males have a stripe, but females do not. At rest, these flies tend to fold one wing over the other. Eggs are long white ovals. And the larval form, or onion maggots, are creamy white, legless, and a little less than 1/2 an inch long.
Onion maggot lifecycle
Adult flies lay eggs on leaves, shoots, and bulbs of host plants. These hosts include onions, leeks, and, to a lesser extent, garlic. Flower bulbs are also susceptible to onion maggot feeding. When the eggs hatch, onion maggots start feeding and feed they do! You can find up to 50 onion maggots in a single bulb! After they have eaten their fill, the larvae move into the nearby soil where they will pupate. These damaged areas provide points of entry for many other fungal and bacterial pathogens.
How to control onion maggots
Crop rotation is your best defense against onion maggots. Since the adult forms can fly, there is only so much you can do. Row covers may help, but it is difficult to time their use properly. Yellow sticky traps can be used to monitor for adult flies.
Luckily for Bay Area gardeners, our cool, wet winters slow larval growth. In our area, more damage occurs while onions are in storage than in the field. You can protect your onion harvest from damage by thoroughly brushing off onions before putting them into storage, and regularly monitoring harvested onions.
Cabbage maggots are a serious pest of plants in the cabbage family (Brassica).
What starts out as a single, tiny fly can turn into 300 squirming, gnawing slugs of destruction in just two or three days. And you may never see them before it is too late. Cauliflower and Brussels sprouts are more likely to be attacked, but broccoli, cabbage, turnips, radishes, rutabagas, and mustard plants are also vulnerable, especially in cool, wet weather.
Cabbage maggot description
Cabbage maggots are the larval stage of the cabbage fly (Delia radicum). Also known as cabbage root flies, root flies, or turnip flies, this dark grey fly is half the size of your average house fly. Maggots are white, legless, and only 1/3 of an inch long, with a pointed head and a blunt behind. Eggs are white and 1 mm in diameter.
Cabbage maggot lifecycle
Eggs are laid in the soil, around the crown of host plants. When they hatch, larvae (maggots) start feeding on fibrous roots and burrowing into taproots. This feeding facilitates entry by pathogens that cause blackleg and bacterial soft rot, and it continues for three weeks before maggots pupate in the soil. In two to four weeks, adult flies emerge to feed on nectar and the whole cycle begins again.
Symptoms of cabbage maggot feeding
These pests are easy to miss, but the damage they cause is obvious. As seedlings and young plants struggle to survive, chlorosis (yellowing), stunting, and even death may occur. Infested root systems are sparse and taproots show obvious tunneling. Established plants are better able to withstand attack, but they will also show stunting and chlorosis. Wilting in the middle of the day can also be a sign of cabbage maggot feeding. Plants will perk back up by morning, but, within a few days, they will be dead. Dark green leaves may show a bluish tinge, but that can be a normal feature of some plant varieties, so don’t use it as a symptom unless other signs are visible. Infested plants should be removed and destroyed. Do not compost infested plants.
Cabbage maggot control
If cabbage maggot carnage is something you need to control, spinosad is moderately effective, according to a 2015 UCANR study. Traditionally, fumigation was used, and organophosphates (diazinon and chlorpyrifos) were applied to soil in concentrations heavy enough to contaminate ground water and kill off non-target species. Obviously, more environmentally safe, sustainable methods are needed. Many of the other insecticides that performed the best in the study are unavailable to the home gardener, and for good reason. You can reduce the likelihood of infestation by using crop rotation, row covers, and proper irrigation.
If you are determined to protect your cole crops, you can also use brassica collars around the base of each plant. A brassica collar is simply a flat piece of plastic, thick cardboard, or heavy fabric that covers the soil around the base of a plant. Cabbage flies are unable to lay their eggs as close as they would like, and many of the larvae simply starve to death before they reach your plants. You can make your own brassica collar, just be sure that the collar opening can be enlarged as the plant grows.
Banding is a way to help your seeds get a better start on life.
As much as making music is a great way to expand your mind and improve your math skills, banding in the garden has nothing to do with tempo or harmonics. Banding refers to the practice of incorporating fertilizer in the soil close to your seeds at planting time. Just picture, in your mind’s eye, a band of seeds planted in the ground, with a band of fertilizer right next to them. As new roots grow, they are sure to find a good meal to help them get big and strong.
It makes obvious sense, but you do have to be a little careful. Banding falls into the “too much of a good thing can be a bad thing” category. According to Montana State University, benefits of proper banding include:
How to band seeds at planting time
Unlike top dressing, which means leaving aged compost or fertilizer on top of the soil, banding requires a little more effort. For the home gardener, we don’t need to get too particular about the depth. Professional, large-scale farmers have this down to an art and science, but we can safely apply our banded fertilizer 3 or 4 inches deep, 1 to 3 inches on either side of the row of seeds being planted. These “starter fertilizers” make valuable nutrients available to early roots, helping the seedling to reach its full potential. Before you jump on the fertilizer band wagon [Sorry, I couldn’t resist], you need to find out what you are working with and which fertilizers are best for your plants.
I’ll say it again: soil test!
You can’t know what to add if you don’t already know what you have. Your soil may have an abundance of phosphorus. Adding more could be detrimental to your plants, and it’s a waste of money. Adding unnecessary fertilizer also puts the environment at risk, you know, global health and all that. Find a reputable, local soil test company and use them. The results are really fascinating and useful. [Over the counter soil test kits are not reliable or useful. Yet.] If your soil already has plenty of everything, banding is unnecessary. If your soil is lacking any of the Big Three plant nutrients, banding can help your seeds overcome this handicap.
Choosing the right fertilizer for banding
All fertilizers are required to provide information about the percentage by weight of nitrogen (N), phosphorus (P) and potassium (K). Think about this for a moment. A 10-pound bag of 10-20-10 fertilizer contains 1 pound nitrogen, 2 pounds phosphorus, 1 pound potassium, and 6 pounds of filler. After you have gotten the results from your soil test, you can select the best fertilizer for your crop.
According to Pennsylvania State Extension, nitrogen and phosphorus are the “key nutrient components in a starter fertilizer.” If all your plants need is nitrogen, blood meal is an excellent choice. Be cautious with fertilizers that contain urea (46-0-0) or diammonium phosphate (10-34-0), as these substances can burn or even kill young plants.
So, find out what’s in your soil. If something is lacking, put it where seeds are sure to find it with banding!
Turnips are a white, cool weather root crop.
Cousin to rutabaga, radishes, and other members of the cabbage family, turnips (Brassica rapa) are grown for the bulbous taproot that looks more like a beet, except that it is white, and its nutrient rich leaves.
Fun turnip trivia: the pink, purple, red, or greenish color of a turnip’s shoulders is a result of being exposed to the sun.
Taste for turnips
Many people believe that they do not like turnips, but this is often because the turnips they tried were too old. Old turnips taste bitter. This is because of a self-defense chemical produced by many members of the cabbage family. Also, some individuals have inherited a pair of genes that make them extra sensitive to the bitterness, so don’t force anyone to try the fruits of these labors. It just might not be possible for them to enjoy the flavor. That being said, young, tender turnips do not contain as much of the bitterness, so harvest early and often! Also, consistent irrigation reduces the chance of your turnips becoming bitter.
Turnip leaves are a popular side dish in the southeast. Tender leaves are less bitter than older leaves. Bitterness can be reduced by pouring off the cooking water and replacing it with fresh water and reheating. Unlike rutabagas, which have a visible crown or neck between the taproot and the leaves, turnip leaves grow directly from the root.
How to grow turnips
Like other root crops, turnips prefer loose soil, but they are resilient plants. They can handle conditions that thwart more gentle crops. Here in the Bay Area, turnips can be planted February through April, and again in September and October. Seeds should be planted 1/2 inch deep, directly into the garden. Seedlings should be thinned to 4 to 6 inches apart, when grown for roots, and 2 to 3 inches apart for greens. Depending on the variety planted, your turnip crop should be ready within 50 to 75 days. Tokyo turnips, which tend to be smaller, are harvestable after only 30 to 60 days!
The life of a turnip
Turnips are biennial plants, which means it takes them two years to from seed to seed. Most turnips grown in fields and gardens never get that chance. Planted in full sun or partial shade, first-year turnips put out roots and absorb as many nutrients as they can, storing them for the upcoming winter months. In the spring of a turnip’s second year, it puts out tall yellow flowers with seeds in pods that look like tiny pea pods.
Turnip pests and diseases
As a Brassica, turnips are subject to attack by caterpillars, whiteflies, cabbage loopers, Bagrada bugs, beet armyworms, and aphids. Aphids can also carry turnip mosaic, a viral disease common to Brassicas. Row covers can prevent damage, but only if they are installed before the problem starts.
Turnips have been grown for over 4,000 years. Pliny the Elder ranked turnips third only to cereals and beans as the most important crops. Turnips were also used in early experimentation with crop rotation.
Give turnips a try in your garden today!
If you grow corn, sorghum, millet, or sunflowers, you will end up with a bunch of dead, leafy stalks standing in your garden. That collection is called stover.
The word stover evolved out of the legal term ‘estovers’ from English history. An estover was the ration of wood and other resources that peasants were allotted from the King’s forests each year. It was a woodsy version of gleaning the fields. Gleaning refers to the practice of allowing peasants and strangers to collect whatever was leftover from a field after the harvest was completed.
Just as straw is left behind after a crop of oats, alfalfa, or wheat is harvested, stover was traditionally left in the field for cattle or other grazers. Some modern mushroom farmers use stover as compost for mushrooms. Dairy farmers often use stover to create silage. Silage is plant material that is cut and crushed and then stored in a relatively airtight silo without being dried ahead of time. This fodder ferments, making more easily digestible. But, I’ll bet that you do not have a silo in your backyard, or cattle to feed. So, what can you do with your stover at the end of the growing season?
The first and easiest use of stover is to add it to the compost pile. Stover often consists of half of your crop. That’s a lot of plant material. Held within that material are nutrients that other plants can use, but only if the stover has broken down. You can compost stover by cutting the heavy stalks into one-inch pieces and keeping it near the bottom of your compost pile. For shorter crops, such as millet and sorghum, I simply cut the plants off at ground level and toss it all to my hens, who make short work of the greens. [The sorghum comes back each year for a continuous supply of greens and seeds for my hens and I always manage to miss some of the millet seeds, so they pop back up each spring, as well.]
In commercial agriculture, stubble cultivation refers to the act of plowing all that stover back into the earth. This returned the nutrients back into the soil and improves soil structure (assuming the heavy farming equipment doesn’t compact the soil too much). In my mind, stubble cultivation is a twist on the Three Sisters Method of planting. Rather than cutting down tall stalks of corn or sunflower, these sturdy poles can be put to work. Simply plant cool weather climbing plants, such as peas, at the base of each stalk. The petioles (tiny stems that attach leaves to bigger stems) make perfect handholds for tiny tendrils. The peas grow up and up and up and you don’t need to install or maintain a trellis! After your pea crop is harvested, you can cut the stalks off at ground level, chop them into bits, and add them to the compost pile. Or, you can use them again, as bean poles!
Other uses for stover
There are other creative ways to repurpose those tall, study stalks before they need to be composted. Here are some of my favorites:
How do you put your corn and sunflower stover to use? Let us know in the Comments!
Parsnips look like white carrots, well, because they are related!
Cousin to carrots, parsley, celery, and other umbels, parsnips (Pastinaca sativa) are native to Eurasia and have been cultivated since ancient times. In fact, parsnips were used as a sweetener before sugar cane made its way to Europe!
Parsnips are a cool weather crop in the Bay Area and other Mediterranean climates. Parsnips can be planted in September, and then again in February, March, and April in our region. If you live in a different area, simply check with your local Cooperative Extension Office for your best planting times.
Parsnip plant description
Parsnips leaves look almost like ferns, with pinnate (branched), toothed edges (margins). Parsnips are grown as annuals, but if you let a few of them go to seed, these biennials can start spreading edible roots in many areas of your foodscape. [Once they start that process, you won’t want to eat them - they get quite woody.] Second year plants can grow 5 feet tall, but your first year parsnip will be significantly shorter, at only 18 to 24 inches. Yellow, umbrella-shaped flowers grow into tiny ‘fruits’ called schizocarps. [How’s that for a fun garden word?]
How to grow parsnips
Parsnips, like other root crops, need loose soil. This makes them well suited to raised beds and container gardening. If you are planting parsnips in the Bay Area’s heavy clay soil, you will want to break up the soil down 18 inches and dig in 3 or 4 inches of aged compost. If you don’t, you will end up with forked and otherwise deformed roots prone to disease. Parsnip seeds should be planted 1/2 inch deep, with a heavy dose of patience. Parsnips seeds are slow to germinate and the plants take up to 4 months to reach harvestable size, but they are worth the wait! These sweet roots lend themselves to seasonings such as ginger and nutmeg, as well as more savory dishes, such as soups and stews. Parsnips can be grown in full sun or partial shade. They prefer slightly acidic soil, so you may need to make some pH adjustments. Seedlings should be thinned to stand 3 to 6 inches apart and be sure to eliminate all competition from weeds.
Parsnips pests and diseases
I had a difficult time tracking down parsnip pests and diseases in the Bay Area. Other regions had plenty to say, but my guess is that the Bay Area is not conducive to growing parsnips commercially, so it gets less attention. Being more than a little determined, I am going to try growing them anyway!
It is my guess that, being a close cousin to carrots and parsley, parsnips will probably have many similar problems. These include armyworms, cabbage loopers, and aphids. Fusarium wilt, powdery mildew, bacterial leaf spot, and alternaria leaf blight may also occur. Other regions mention how celery fly larvae may tunnel into parsnip leaves, much like leaf miners. These pests can harm young plants, so remove infested leaves if you see them. I also found plenty of warnings about carrot flies. Carrot fly larvae are likely to attack parsnip roots, providing points of entry for canker and other fungal diseases. These pests are attracted to the smell of bruised plant tissue, so be gentle to your parsnips!
According to Wikipedia, parsnip canker is a real problem when growing this crop. Parsnip canker shows itself as orange-brown or black areas on the crown and shoulders. Also, the roots will crack. This condition is more likely to occur when seeds are planted in cold, wet ground that is too alkaline. It sounds, to me, that poor drainage is a parsnip’s worst enemy.
On the upside, many moth and butterfly larval forms use the flowers and undeveloped seeds of second year parsnips as a major food source. So, allowing a few parsnip plants to complete their lifecycle not only gives you free parsnip seeds and plants, it also adds biodiversity to your landscape and provides food for many beneficial insects!
Like many other root crops, parsnips taste sweeter after they’ve experienced a little frost. Since our ground is not likely to freeze, we don’t need to worry about getting our parsnip harvest out of the ground before it does. Other regions are not so lucky. Before you harvest your parsnips, however, be sure to wear gloves. Parsnips may be good sources of folic acid, potassium, fiber, and vitamins C and K, but they also have a powerful self-defense mechanism. Parsnip sap is toxic. If your skin is exposed to sunlight after handling parsnip leaves and stems, you are likely to get a rash. So, wear gloves.
Give these sweet root crops a try this winter and let us know what you think!
Persian limes with brown bottoms have stylar end rot.
Also known as stylar end breakdown, stylar end rot generally affects Bearss, Tahitian, and other Persian limes species, though it has been seen in other lime and lemon varieties. Stylar end rot is a physiological disease, which means it is not caused by pests or pathogens. Instead, stylar end rot is caused by too much heat and drought. Even though limes, lemons, and other citrus have thick, waxy skins to protect themselves from the sun’s heat and drought conditions, sometimes that protection isn’t enough.
Symptoms of stylar end rot
The stylar end of a fruit is the part with the dried up flower petals, opposite the stem end. Stylar end rot starts out as a small, grayish sunken area, at the stylar end, that slowly becomes firm and leathery. Affected areas can spread to cover 1/4 to 1/2 of the fruit, which is often invaded by bacteria or fungi. The tissues inside break down and turn brown or pink. Diseased fruit can be added to the compost pile, but only if it is free of other fungi and bacteria. Otherwise, toss it in the trash. Stylar end rot found on guava has been found to be caused by a fungi, Phomopsis. Some fungal diseases exhibit similar symptoms:
Mealybug destroyers, also known as mealybug ladybirds, are close cousins to our beloved lady beetle, or lady bug. In fact, many members of the Coccinellidae (kox-ih-NELL-a-DEE) family are beneficial predators, but not all. With a name like mealybug destroyers, you know that your garden plants are going to love this tiny beastie!
Mealybug destroyers (Cryptolaemus montrouzier) are native to Australia. They were brought to the U.S. in 1891 to combat California’s citrus mealybugs. Most mealybug destroyers cannot handle cold temperatures, but some populations have remained along coastal areas.
Mealybug destroyer identification
Like their close cousin, the lady bug, mealybug destroyer adults have the same dome-shaped body and short, stubby antennae. [That's a pretty cute little face, too, wouldn't you agree?] Mealybug destroyers, however, have black wing cases (elytra), with orangish-brown shoulders and rear end. Adults are only 1/6 of an inch log, so you may never notice them. If you decide to take a closer look with a hand lens, you might be able to see that females have dark brown forelegs and males’ forelegs are light brown. The larval forms, which can reach 1/2 inch in length, are often mistaken for wooly aphids or mealybugs, because of their elongated, alligator shape and waxy, white filament covering. Yellow eggs are laid near mealybug eggs for easy access to their favorite food supply.
Mealybug destroyer diet
A single mealybug destroyer may eat 250 mealybugs in its short lifetime. They also feed on soft scale insects. And it is not just the adults who hunt down and kill our garden enemies. While adults chomp and chew, larval forms pierce and suck the life juices from many sap-sucking garden pests.
So, why would a gardener care about mealybugs? Cousin to aphids and whiteflies, mealybugs are sap eaters. They feed on new buds, shoots, and leaves, causing erratic or reduced budbreak, slowed growth, and twig dieback. Mealybugs are frequent pests to basil, grapes, stone pine, pomegranate, chamomile, apple, plum, pear, peach, ferns, orchids, and, well, quite honestly, pretty much everything growing inside or outside of your home. Mealybugs produce honeydew, which provides the perfect growth medium for sooty mold. They can also carry bean mosaic. That’s why.
Attracting mealybug destroyers
It is highly unlikely that there are any mealybug destroyers in your neighborhood to attract. They simply cannot handle winter weather. So, you will probably have to buy mealybug destroyers each spring. What you can do, to prevent them from flying away as soon as they arrive, is to provide biodiversity. This means installing a wide variety of plants, with various heights, shapes, and colors. And avoid those broad spectrum insecticides.
Mealybug destroyers may not occur naturally in the Bay Area, but they sure can help maintain the balance of power in your foodscape!
Flea beetles hop from plant to plant, chewing tiny holes in leaves as they go.
We are not talking about the blood-sucking, disease-carrying fleas on squirrels. Instead, flea beetles are plant pests. Generally, they do not cause a lot of damage. After all, each flea beetle is only 1/16 to 1/8 of an inch long! If your plants are hosting enough of them, however, the damage can slow growth or provide points of entry for bigger problems. Let’s see what your plants are up against.
Flea beetle varieties
There are dozens of leaf beetle species. Here in the Bay Area, you are more likely to see these particular pests:
Flea beetle host plants
Flea beetles feed on many families of edible garden plants:
Also, carrots, corn, and sweet potatoes may find themselves on the menu. Flea beetles are also attracted to yarrow, but this is a good thing. Yarrow acts as an insectary. Beneficial insects have evolved to lay their eggs in plants such as yarrow, knowing that flea beetles and other pests will provide their young with an easy first meal. Other beneficials, such as big-eyed bugs, will also feed on flea beetles, so go easy on the pesticides. Pesticides don’t work very well on flea beetles anyway - they simply hop away.
Flea beetle damage
Pitting and small, irregular holes in leaves may merge to create raggedy areas. The holes are smaller than the damage caused by shot hole disease. Shot hole disease holes usually begin as 1/10 to 1/4 inch diameter red or purplish spots. There may be a pale green or yellow ring around each spot. As the dead tissue dries up and falls away, the shotgun blast look will appear. Small, irregular leaf holes may be caused by springtails, but it is more likely to be flea beetles. Fruits and roots may also be damaged by flea beetles.
Flea beetle lifecycle
Flea beetles lay tiny eggs in weeds, plant debris, and in the soil surrounding their favorite food plants. After the eggs hatch into thin, white larva, feeding may begin above or below ground. After a month or so, the larva pupate in the soil. When they emerge as adults, they use their big jumping legs to go wherever they want to feed.
Flea beetle control
Since pesticides are not very effective on flea beetles, other controls must be used, if control is actually needed. In most cases, it isn’t. If an infestation starts to cause serious damage, use basic sanitation in the garden. Removing all those tiny hiding places can make life difficult for flea beetles. Reflective mulch and white sticky traps can also be used, and row covers may block pests from reaching plants in the first place. Once they are present, you can lightly sprinkle the area with diatomaceous earth (DE). Apparently, flea beetles don’t care too much for sulfur, either.
Some commercial growers actually vacuum off heavy flea beetle infestations, but I don’t recommend it for the home gardener. You vacuum cleaner would never be the same!
Chinese cabbage refers to two different cool weather crops that lend themselves to Bay Area fall and winter gardens.
Chinese cabbages (Brassica rapa) are variations on the lowly turnip. The two subspecies we most commonly see are forms of Napa cabbage (var. pekinesis) and bok choy (var. chinensis). These healthful foods have been grown in China since before the 15th century.
Also known as Korean small cabbage or celery cabbage, Napa cabbage has a milder flavor than more domestic varieties, but it packs a nutritional punch that’s difficult to beat. According to a study conducted by the Centers for Disease Control in 2014, Chinese cabbage ranks second only to watercress as a nutrient dense food. Napa cabbages come in both head and loose leaf varieties. Napa cabbages can be planted in the Bay Area twice each year: first, February through April; and again, August through October.
Unlike the Napa cabbages, bok choy does not form heads. Bright white stalks give way to dark green blades, growing in a cluster, much like celery. Bok choy can be planted in the Bay Area in September and October, and then again, February through April.
How to grow Chinese cabbages
These biennial plants are generally grown as annuals. If you allow your plants to go to seed, you can create a seasonally perpetual crop within your landscape. To begin, find a location with full or partial sun and well-drained soil. Adding aged compost to the planting bed ahead of time can provide a nutritional boost to your plants and improve soil quality, while you’re at it. Chinese cabbages can also be grown in containers. Use pots that are 8 to 12 inches across and 18 to 24 inches deep. Seeds should be planted 1/2 inch deep and successful seedlings should be thinned to 12 - 18 inches apart. These plants do not transplant well, so it is better to put them where you want them right from the beginning.
Pests and diseases
Being closely related to broccoli and cauliflower, Chinese cabbage is subject to many of the the same pests: aphids, flea beetles, armyworms, loopers, cabbageworms, leaf miners, and millipedes. Common diseases include white rust, damping-off, yellow virus, clubroot, black rot, and bottom rot. Many of these diseases can be prevented by allowing soil to dry out between waterings.
Harvesting Chinese cabbages
Chinese cabbages are good candidates for succession planting. If you start one new plant per person every two weeks, through fall and winter, you will have an abundance to harvest. You can extend that harvest by only cutting away outer leaves on an as-you-need-them basis. These plants will continue to produce inner leaves through the growing season.
Like other cabbages, these plants to not produce a lot of ethylene gas. Ethylene gas is what makes fruits and vegetables ripen. Cabbages are, however, very sensitive to the ethylene gas produced by other plants, so it is a good idea to keep harvested leaves or heads in a plastic bag in the refrigerator. Or, your can always try your hand at fermenting some cabbage for your very own kimchi!
Idioblasts are specialized plants cells that are very different from the cells around them.
Most plant cells are grouped together with other, similar cells: leaf cells with leaf cells, root cells with root cells, and so on. Hidden within these normal groupings are cells called idioblasts.
Scientists believe that idioblasts are the precursors to many specialized cells, such as stomata, glands, and guard cells. When idioblast cells divide, they often create daughter cells different from themselves. These mutations have given rise to much of the diversity within the plant world. At the same time, many idioblasts have remained the same over time, providing important functions within a plant. According to Albert Paul Kausch, in his 1985 doctoral thesis, The development, physiology, and function of selected plant calcium oxalate crystal idioblasts, no one really knows how or why idioblasts form.
Most commonly, idioblasts are storage cells. But some idioblasts hold a defensive arsenal of poisons and pointy crystals!
When botanists and scientists talk about idioblasts, they divide them into several groups, depending on function.
Some idioblasts are simply storage cells. They may store pigment, food, waste products, water, resin, latex, oil, or tiny stones of silica (phytolith). Until recently, it was not understood why plants contained silica. Then, some scientists tried growing plants in soil without any silica. Many of these plants flopped over. Mystery solved. Sort of. Then, another group of scientists, led by Fergus P. Massey, proposed that plants evolved to contain silica for more than just structural support. They claim that plants absorb these minerals as a defense mechanism. Massey and his team point out that silica in plants tends to wear down the teeth of those who eat them. There is debate about the truth behind this assumption. You decide.
Idioblasts as manufacturing centers
Other idioblasts do more than just store materials. Some idioblasts actually manufacture important compounds. For example, avocado skins have idioblasts with antifungal properties. Other idioblasts produce mucilage carbohydrates (mucus cells) that store water. Other idioblasts, called phenolic cells produce and store carbolic acid to be used as defensive weapons.
Idioblasts as weapons
While we consider herbivores to be mostly harmless, plants do not share that view. Rooted to one location, and without claws or fangs, plants have to get creative when it comes to defending themselves against grazers and other plant eaters. This is where idioblasts get really interesting. Some idioblasts contain biforine cells. Biforine means having two doors. [Isn’t that a great word?] These cells are oval-shaped with openings at each end. When something (or someone) bites the plant, breaking the cell, crystals of calcium oxalate shoot out, poisoning or irritating the attacker! These oxalates are produced in the vacuoles of the idioblasts. Oxalates are toxic to the plant, too, but the plant protects itself by binding the material up in crystals. These crystals come in many shapes. They may look like a grain of sand, a pencil (styloid), a needle (raphide), or prismatic (isodiametric). Bundles of raphides or prismatics are called a druse.
Plants that use these weapons
Many plant families rely on druses stored in idioblasts for protection. These families include:
Botanists believe that plants also use these calcium oxalate-filled idioblasts to provide structure to the plant, and as a way to store calcium.
This information may not help your grow brighter flowers or more delicious tomatoes, but your mind needs to grow, too! And who can resist a word like idioblast?
One or two minutes may be all the warning you get when it comes to fire.
In light of all the fires raging in Northern California, I am dedicating today’s post to fire safety and how it pertains to the plants around your home.
Several years of drought have killed hundreds of millions mature trees across the country. In California, over 102 million trees have died since 2010, and 62 million trees died in 2016 alone! Many of the remaining trees are not as healthy as they could be, due to bark beetle infestation and disease. These trees have more dead leaves and dry twigs, making them susceptible to fire.
Fire in landscapes
You learned it back in elementary school: fire needs fuel, heat and oxygen to keep going. A single spark can land on dry grass, move to a shrub, climb a tree, and then leap to your home, taking everything you own with it. It can also take your life. Gardening for fire safety means interrupting that spread. Rather than allowing fire to move through your landscape using shrubs and trees as a super highway, you can create spaces that slow or stop the flames.
California state law (Public Resources Code 4291) requires that all rural homes have a 100-foot defensible space. Suburban homes face different challenges, but fire safety is still critical and many of the suggestions still apply. Each county has its own set of ordinances, so be sure to check with local authorities. Even without the law, fire safety around your home just makes good sense.
Defensible space can slow or stop the spread of fire. It also helps keep you, your family, and our heroic firefighters safe. Your defensible space is made up of two zones.
Zone 1 - According to CalFire, the first zone consists of a 30-foot perimeter around any buildings, sheds, or decks on your property. Maintaining this zone means:
Zone 2 - The second zone extends 100 feet from your home. To maintain Zone 2:
Spacing plants and trees
By creating space between trees and shrubs, the spread of fire can be slowed or stopped. The spaces are both vertical (up and down) and horizontal (side to side). To maintain safe vertical space, remove any tree branches that are 6 feet from the ground or less. In areas prone to wildfire, bushes growing near tree canopies need three times their height before the lowest tree branches to prevent fire from spreading. This means that a 4 foot tall shrub would need 12 feet before the closest tree’s lowest branch to be fire safe.
Horizontal spacing is a function of slope. Areas that are flat or with slopes less than 20% can allow trees to be 10 feet apart. Shrubs should be two times their height apart. This means 4-foot shrubs should be 8 feet apart to be safe. Slopes of 20 to 40% require shrubs to be 4 times their height apart and trees need 20 foot spacing. To keep slopes greater than 40% fire safe, trees should be 30 feet apart and shrubs need to be 6 times their height apart. These rules apply to rural properties, but you can apply them to your suburban home, as well.
What about all that mulch?
Nearly everything you read in The Daily Garden reminds you of the benefits provided by mulch: moisture retention, weed reduction, temperature stability, reduced soil compaction, and so on. But what about flammability? Does all that ground cover create a path for fire? Luckily for us, a group of fire and gardening professionals got together in Nevada to test various types of mulch. This is what they learned about each type, listed in order of worst to safest, all used at a depth of 2- to 3-inches, unless stated otherwise:
Use fire-resistant plants
We all know that green plants burn a lot more slowly than dead, dry plants. And there are no truly fire-resistant plants. If it gets hot enough, anything can burn. You can help keep your home safe by planting low-growing, high-moisture plants closest to your home. Succulents certainly come to mind. When deciding where to install plants, imagine your home in the bottom of a shallow bowl. The height of your plants should get taller as your move away from the building. This would help draw fire away from your home, rather than towards it. The following plants are less likely to be a fire hazard:
The added advantage to many of these plants is that they have evolved to withstand drought, which means many of them require less water. UCANR provides a list of low-risk, Fire-safER plants. Despite their name, evergreens, such as pine and fir, are far more flammable than the hardwoods.
Create a fire safety plan. If you live in rural areas, use the Wildfire Safety Plan. If you live in a city or suburban area, use the plan provided by the National Fire Protection Association. Seriously, people. It takes 20 minutes and could save your life.
To learn more about how likely fires are in your area, check out the maps provided by the National Park Service. Also, CalFire offers a homeowner’s fire safety checklist that deserves your attention.
In case of high fire risk
If fire risk is especially high, you may want to take the following actions before it is too late:
Bottom line: keep your plants green and healthy and move flammables away from your home.
Above all else, in case of fire: GET OUT AND STAY OUT. Everything else is temporary.
Autumn colors are caused by senescence.
Senescence is the life stage of a plant or plant part when its metabolism slows prior to dying.
Our lovely fall colors are caused by a deciduous tree’s inability to maintain chlorophyll levels within its leaves. Chlorophyll, being green and abundant most of the time, masks the other colors that are alway present within a leaf. Shorter days and cooler temperatures trigger the tree to form a layer of cork at the base of each leaf, blocking the flow of water and nutrients and interfering with the leaf’s ability to produce chlorophyll. Eventually, the other colors can shine through. The veins of a leaf are the last part to turn color because it is the last place nutrients were available.
Autumn leaf color and the final days of a flower’s life are examples of developmental senescence. Developmental senescence occurs at the cellular level in all life stages. The seed leaves of a bean plant experience senescence when they wither and fall off. The mature leaves of the same plant will also exhibit senescence when they die. Ultimately, the metabolism of the entire plant will slow to the point of death. In each case, developmental senescence is triggered from within the plant.
Sometimes senescence is not developmental. It can also be induced for laboratory research, or as a result of injury or stress. Water stress can trigger senescence. A large plant with many leaves may be unable to maintain its canopy in a drought. Rather than risk death, it absorbs water and nutrients from outer leaves and then seals them off from the food supply, allowing them to fall away. Sunburn can also cause senescence. As an under-hydrated leaf receives direct sunlight, the cells most damaged slow their metabolism and relinquish their water and nutrients to the surrounding cells.
As seasons change and plants age, you will see many examples of senescence, but the colors of autumn are my favorite!
The Calvin cycle describes what happens to light energy after it has been absorbed into a leaf.
Put on your steampunk magnifying glasses because, today, we are going deep into the molecular level of leaves to learn how they make energy from sunlight.
Also known as the Calvin-Benson cycle, Melvin Calvin won a Nobel Prize in Chemistry for figuring this out. That was in 1961. Until Melvin’s research was complete, everyone thought that photosynthesis consisted of chlorophyll interacting directly with carbon dioxide to create edible organics (sugars) for plants. Instead, his research taught us that light energy causes chlorophyll to trigger plants to produce those organic compounds for themselves!
So, how does photosynthesis work?
Photosynthesis occurs in two steps. The first step is the light dependent reaction. This is when the sunlight is absorbed and transformed. To do this, electrons are torn from water molecules, creating oxygen as a waste product. When this happens, hydrogen (H) is released and used to create two compounds: nicotinamide adenine dinucleotide phosphate (NADPH) and adenosine triphosphate (ATP). The second stage of photosynthesis is the light independent reaction, or the Calvin cycle. This is when the ATP is converted into glucose.
Each stage of the Calvin cycle has its own enzyme. Enzymes are chemical catalysts that trigger change. After light energy has entered a plant through the stoma and been converted into ATP and NADPH, the light-independent (or ‘dark’) aspect of photosynthesis can begin. There are four stages to the Calvin cycle:
For your chemistry buffs, here's the equation and a graphic:
In the illustration above, atoms are represented as black (carbon), white (hydrogen) red (oxygen) and pink (phosphorus).
For the rest of us, try this story for a more memorable form:
Rubio marries Connie. Connie has twins. One twin becomes a cook. The other twin works family business and marries a girl just like mom. And they have twins. And so it goes….
Factors that interrupt the Calvin cycle
Any interruption in photosynthesis leads to chlorosis, or yellowing. Chlorosis can be the result of insufficient light (epinasty), disease, a lack of mycorrhizae, or sunburn. Other factors that interrupt the Calvin cycle include:
If you see chlorosis, it means your plant is starving. By learning about the Calvin cycle, you may be better equipped to figure out what is wrong with your plants. Get growing!
* RuBisCO - ribulose bisphosphate carboxylase/oxygenase; believed to be the most abundant enzyme on Earth (Wikipedia)
Phoresy describes the relationship between two organisms in which one is a hitchhiker, but not a parasite.
The fleas that catch a ride on your dog or cat are parasites. They catch rides and then drink the blood of our beloved pets. This is not phoresy. Now, picture a person riding a horse. Person plus horse equals phoresy. The person is being transported by the horse, but is not a parasite.
In many cases, electron microscopy is needed to actually see phoresy in action. And many phoretic insects lose the ability to catch a ride once they have reached a destination. Like many other insects, those that use phoresy may go through several very different life stages, such as phoretic, parasitic, and reproductive stages.
In nature, phoresy can bring both pests and beneficials to your garden. Here are just a few of the situations in which phoresy occurs.
We may love to see hummingbirds flitting through the garden, but you should be aware that hummingbirds may carry flower mites. Flower mites are tiny, nectar stealing pests that run up a hummingbird’s beak as it feeds. Grabbing ahold of the hummingbird’s nostrils, flower mites then go for a wild ride in hopes of reaching a new food source. When the hummingbird stops to feed at a different flower, the mite runs down the hummingbird’s beak to gorge on as much nectar as it can before hopping another ride to yet another flower.
Moving in the opposite direction, it has recently been discovered that varroa mites, the bane of honey bees, are phoretic. These devastating parasites of the honey industry lie in wait for unsuspecting honey bees to visit a flower. As the bee collects nectar and pollen, varroa mites catch a ride that ultimately takes them to the hive. These parasites suck the life fluids from developing and adult bees. These pests also carry viruses that infect honey bees. Varroa mite infestations can kill an entire hive, if left untreated. Varroa mites are just one aspect of the global problem of colony collapse disorder.
Male ground bees are seduced by blister beetle larvae into carrying them to female ground beetles, phoresy style. Blister beetle larvae emit a pheromone that is similar to the perfume used by female blister beetles to attract males. When male ground bees approach, the blister beetle larvae attach themselves to the male bees. After recovering from their disappointment, the male bees continue their search for a female. When she is found, the male bee blindly does his business as the blister beetle larva moves to the female bee. When she returns to her nesting area, the larva jumps off and begins feeding on everything it can - nest, provisions, and eggs.
Pseudoscorpions are tiny beneficial insects that feed on ants, thrips, small flies, springtails, carpet beetles, clothes moth larvae, booklice, and spider mites. They also get around using phoresy by catching rides on many different flying and crawling insects. In some cases, they even provide a service to the carrier insect by eating its parasites along the way!
One phoretic wasp, Trichogramma, catches rides on mated female imported cabbage moths to reach areas where eggs have been laid. These beneficial wasps then parasitize the eggs, making our jobs as gardeners so much easier. Research on this behavior is new, but very exciting!
Greenhouses provide the warmth, sunlight, and moisture that plants need to thrive. The same is true for thrips, whiteflies, leafhoppers, and fungus gnats, just to name a few. While reputable greenhouse growers do their best to eliminate pest phoresy on the plants they sell, it still happens. Many imported pests and diseases are brought into new areas through phoresy. When you bring plants home, you also risk bringing phoretic pests and diseases. This is why it is so important to create a quarantine area. Forty days and nights goes a long way toward sorting out and preventing more serious problems.
So, quit "phoresing" around! Go take a closer look at your plants and the insects that call them home. You may be surprised to see what’s out there!
Succession planting takes a long term view of garden usage. Instead of simply planting whatever seed packets looked best in the garden catalog, successful gardeners look at the same space over time to see what can be planted after the current crop.
Benefits of succession planting
Succession planting makes efficient use of fertile ground by leap-frogging plants and crops for a continuous harvest. This eliminates the deluge of every plant reaching harvestable size within the same week. That’s great if you’re putting up tomato sauce, but it can be a bit much when talking about 20 Romaine plants! By changing the life stage and/or plant type in any given bed, the odds of total crop failure due to pests or disease are reduced. Growing plants at various life stages in the same place also cuts back on the amount of real estate available to weeds. Finally, planting fast-growing crops with slow-growing crops makes good use of soil that might have otherwise gone fallow.
Different methods of succession planting
In its simplest form, succession planting refers to following one crop with another crop. This is generally done as the weather changes, following a summer crop with a cool season crop. But there is more to it than that. In addition to consecutive plantings, there is also staggered planting, intercropping, and varietal planting.
Varietal planting means installing different varieties of the same plant in the same place, at the same time. These varieties have different maturity dates, providing a continuous harvest. You can fine tune your varietal plantings by taking note of days to maturity and mature size information on seed packets. You may be able to start with an early maturing variety, followed by a mid-season harvest, then a late-season harvest. You may even be able to squeeze in yet another early harvest at the end.
Staggered planting refers to planting seeds of the same plant in the same area, but on different days. This extends the harvest season, providing a continuous, smaller harvest of the same plant. Staggered planting is best suited for lettuce, spinach, radishes, beets, carrots, and peas. For most of these crops, you can start a new set of seeds every week or two, for the best possible production.
Intercropping puts different crops together in the same place, at the same time. This allows gardeners to make use of soil resources that might have gone unused with a single crop. It also increases biodiversity, reducing potential pest and disease problems. One example of intercropping is the Three Sisters Method of growing beans, corn and squash together. Intercropping is the scientific basis behind the Companion Planting craze. I’m sorry, but there are no magic pairings of plants that “like” each other. There are structural and developmental needs of different plants that either support one another or don’t interfere with each other, while growing in the same space. Basic intercropping pairings include:
Planning for succession planting
Your can take advantage of the benefits of succession planting, simply by growing two seasonally different crops in the same bed. As one crop is winding down, the next season’s crop can be getting started. Or, you can get really in-depth into this concept by investing some planning time. To make the most out of your garden space with succession planting, you will need to know the following:
Here in the Bay Area, our growing season is nearly year round. So the next step will be to collect information on all the plants you want to grow. You can do this with pencil and paper, in a spreadsheet, or you can clean off a big table and start moving seed packets around into different groups until you reach what looks like a good plan.
Do yourself and your garden a favor and take note of what works and what doesn’t. Just remember, every garden is different, every year is different, and sometimes we are simply unlucky when it comes to temperature extremes, pest infestations, and nutrient deficiencies. Succession planting can offset some of those problems.
You can grow a surprising amount of food in your own yard. Ask me how!