Plants may not have an active immune system, but that doesn’t mean they passively roll over and take whatever hits them. 

When pathogens strike, plants can respond in two ways to prevent infection: they use pre-existing structures and chemicals and activate responses triggered by the presence of a pathogen.

Pre-existing defenses

Just as our skin blocks many pathogens from entry, a plant’s skin, or epidermis, does the same thing. That’s why insect feeding and mechanical damage can increase the chance of a disease taking hold - something has already breached the plant’s first line of defense. Plant cell walls also block viruses, bacteria, and fungi. Unlike our human immune system, which uses white blood cells to hunt down and destroy invaders, plant cells have antimicrobial defenses built right in. These defenses take the form of saponins, glucosides, and antimicrobial proteins. Enzyme inhibitors can also stop some pathogens from feeding on the plant. Plants also have chemicals that can neutralize toxins created by a pathogen. Finally, receptors can recognize a pathogen and alert the plant to take further action.

Inducible plant defenses

Once a pathogen is recognized, plants reinforce their cell walls and produce defensive chemicals such as hydrogen peroxide, antimicrobial enzymes, and proteins. In some cases, plants have evolved a ‘hypersensitive response’ that kills the healthy tissue surrounding an infection to block further infection to neighboring cells.

Disease resistant varieties

Rather than treating a disease after it occurs, you can grow plants that defend themselves. Installing resistant plants reduces the need for pesticides and fungicides. When shopping for plants, look at the plant label to see if that particular plant is resistant to diseases that tend to appear in your garden. Plant labels use the following codes to designate specific disease resistances:

• A Alternaria stem canker
• F Fusarium wilt
• N Nematodes
• T Tobacco mosaic virus (TMV)
• St Stemphylium gray leaf spot
• V Verticillium wilt

For example, a plant label with VFN displayed tells you that the plant is resistant to Verticillium wilt, Fusarium wilt, and nematodes. While not a guarantee against disease, it does mean the chances are significantly lower.

You can help your plants fight disease by selecting resistant varieties, spacing plants properly, employing crop rotation, and providing adequate water and nutrients. Also, be sure to sanitize your tools regularly, to halt the spread of disease from one plant to another.

Cousin to the dreaded MedFly, melon flies, and spotted wing drosophila, just to name a few, Mexican fruit flies (Anastrepha ludens), or MexFlies, are a major agricultural pest. Quarantines are part of the ongoing battle against fruit flies, so it’s a good idea to check your state’s quarantine listing, or your local Department of Agriculture, periodically to see if your area is included.

History of Mexican fruit flies in the U.S.

First found in the U.S., in Texas, in 1903, Mexican fruit flies were seen again in 1927. By 1954, they had spread to Florida, Arizona, and California. It is estimated that these pests have cost farmers $1.44 billion in damages. Mexican fruit flies are subject to eradication programs that include capturing, sterilizing, and releasing males that interrupt the breeding cycle.

Mexican fruit flies have been expanding their range for several years now, and it’s not simply by catching a ride on an infested piece of fruit. Commercial agriculture brings crops to non-native regions, introducing them to local pests and diseases. For example, the mango, from India, only became a popular food of Mexican fruit flies after it started being grown in Central American and Mexico.

Host plants

Mexican fruit flies prefer grapefruit, oranges, tangerines, mango, apple, peaches, nectarines, avocado, and pear. More recently, they have been found on figs, bananas, prickly pear cactus, cashews, papaya, guava, pomegranate, peppers, tomatoes, squash, beans, quince, Japanese persimmon, passionfruit, pummelo, and arabica coffee. [Coffee?!!?} Not only is the Mexican fruit fly range expanding, but so is their diet.

Mexican fruit fly description

Slightly larger than a housefly, Mexican fruit flies are 1/3 to 1/2 of an inch long. They have a yellow or brown body and distinctive wing patterns. Also, adult females have extra long ovipositor sheathes (egg-laying tubes). The wing patterns include a costal spot (C), an inverted-V, and a sideways S shape. Larvae are slender white grubs with mouth hooks, and a slightly flattened back end.

Mexican fruit fly lifecycle

As far as fruit flies go, this particular species is relatively long-lived. Individuals can survive for 11 to 16 months.  Females lay over 1500 eggs in their lifetime. Eggs are laid in groups of 10, on the skin of a fruit, preferably one that is slightly damaged. This provides an easy point of entry for Mexican fruit fly larvae, along with many other pests and diseases. In a week or so, after being deposited, the eggs hatch out larvae that burrow into the fruit and start feeding. As they feed, the larvae take on the color of the fruit their are eating, so you may not notice right way, after taking a bite of an infected fruit.

​Larval feeding continues for 3 or 4 weeks, depending on temperatures. Then, larvae drop to the ground, where they pupate in the soil. During this seeming pause in development, the slug-like larva is converted into a winged adult that begins breeding immediately after emerging, starting the whole process over.

Controlling Mexican fruit flies​

Because they spend most of their lives inside fruit, insecticides are not effective against Mexican fruit flies in the larval, egg, or pupal stages. There is a tiny, repeated window of opportunity for treatment of adults, but only if direct contact is made with the insecticide. Generally, adults will simply fly away from treated trees and return a few days later, after it has worn off. Commercial growers use complex bait and trap methods that are unavailable to small scale growers.

So, the only thing you can do if you suspect that Mexican fruit flies have found their way to your garden is to immediately contact your state's Pest Hotline, or your local Department of Agriculture. It is best to leave controlling these pests to the pros.

Olive knot is a bacterial disease of olive and oleander caused by Pseudomonas savastanoi pathovar (pv.) nerii and P. syringae pv. savastanoi. These bacteria are like evil twins that don’t cause serious harm but are still a pain to be around.

​Symptoms of olive knot

The knobby bit you see is called a gall. Galls are swollen, distorted, woody growths that can girdle stems and twigs. The P. savastanoi pathovar (pv.) nerii bacteria is the one that causes the galls on both oleander and olive twigs. It also forms galls on the leaves and flower buds of oleander. The P. savastanoi pv. savastanoi twin only affects olive, causing galls on twigs, stems, and leaf nodes.

Olive knot lifecycle

The bacteria responsible for olive knot enter the tree through pruning wounds, leaf scars, frost cracks, and sun scald wounds after traveling on wind and rain. Infection occurs in autumn and winter, but symptoms do not appear until late spring or early summer. The bacteria live in the galls they create and on the surface of twigs, leaves, and fruit.

To prevent olive knot in your garden or foodscape, plant disease-free rootstock, avoid overhead watering, and prune off any infected material during the dry season, disposing of infected material in the trash. Be sure to sanitize your tools afterward.

Fixed copper sprays (one in the autumn and two in spring) can help prevent and treat olive knot infections, but there is no sure cure. While this bacterial disease is not dire, it is spreading and becoming more of a problem. Due, in part, to the popularity of a particularly susceptible cultivar, the Manzanillo olive.

Maintaining a nursery bed takes up very little time or space, but it can save you a lot of money on plants.

What is a nursery bed?

A nursery bed may simply be a plot of ground, tucked away in a corner of the yard. It may be a slightly raised area, walled in with cinderblocks or scrap lumber. Nursery beds do not have to be pretty. They simply need soil, water, and sunlight. If you want to get fancy, you can add corner posts to support protective netting or shade cloth. Again, looks are not important.

​Start seeds in a nursery bed

Vegetable seeds can be started in a nursery bed, and grown there until they are big enough for transplanting. This is an excellent tool for succession planting. As you wait for the current crop to wind down, your next season’s crop is already on its way! Nursery beds are also a great place to start plants that can be used to fill empty spots as they occur. As a tomato plant gives up the ghost, simply cut it off at ground level and install a cheery chrysanthemum in its place! Viola!

Transplant recovery in a nursery bed

Most gardeners feel frustrated by thinning young seedlings. A nursery bed offers the perfect place to put the removed seedlings, allowing them a chance to recover from the ordeal and, possibly, grow to a large enough size to be moved elsewhere, or gifted to a friend or neighbor.

Propagating with a nursery bed

If you want to try you hand at vegetative propagation, nursery beds provide an easy starting point for cuttings and divisions, allowing them time to recover and to develop new roots before being moved to more permanent locations. Nursery beds also provide a good location to start parent plants that will ultimately be divided into many smaller plants (for a tiny fraction of the cost of buying all mature plants).

Nursery beds for hardening off
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Delicate seedlings may need a transitionary period before they can handle being planted in the garden. With the addition of shade cloth or old glass windows, cold frame style, you can give these babies a taste of the great outdoors without exposing them to more than they can handle.

How to make a nursery bed

While you want your nursery bed to be convenient to the rest of the garden (and a hose bib), it can easily be tucked away behind a shed or some shrubs, as long as it gets at least 6 to 8 hours of sunlight each day, and is relatively level. Being sheltered is actually a bonus for a nursery bed, as it helps block strong winds.

Use these steps to create your own nursery bed:

1. Measure off the area to be used.
2. Clear the area of any weeds or other existing plants. [If particularly tenacious weeds are present, cover the area with several sheets of newspaper to block sunlight.]
3. Add a perimeter of some sort: cinderblocks, scrap wood, bricks, logs, whatever you have handy.
4. Add 4 to 6 inches of aged compost.
5. Fill the space the rest of the way with high quality potting soil, up to an inch or two of the top of your nursery bed wall.

Nursery beds are different from raised beds in that they are designated as an unplanned, layover location, rather than a permanent home.

Finally, if you have a nursery bed set up and know that you won’t be using it for a while, it makes a great place to age compost. The nutrients left behind will be exactly what all those baby plants need to thrive!

Hesperidium is the name given to certain types of fruits.

Hesperidia are berries with a tough, leathery skin that tends to be bitter.

If you cut a hesperidium open, you will see separate compartments, called carpels. Within these carpels, you will see hundreds of tiny, fluid-filled vessels that are made out of specialized hair cells. These vessels are called vesicles.

Bud scar may sound like a great punk band name, but knowing how to recognize this tiny bit of plant anatomy can come in handy.

At the tip of most twigs is an area of meristem tissue. This plant tissue can turn into several different types of plant cells. When the tissue grows upward, to continue the trunk of a tree, or a branch stem, it is called apical meristem, or a terminal bud. In this sense, terminal does not mean lying on its death bed. Rather, it refers to the bud at the end of the branch.

As these terminal buds burst forth with new growth, the protective scale normally falls away, leaving a bud scar. Bud scars look like rings around stems and branches of trees and other woody plants. Bud scars are from the terminal bud on a stem. These marks are different from leaf scars. Leaf scars occur at the point of attachment for a leaf, after the leaf has fallen off. Just above a leaf scar, there is usually a lateral bud that can grow into a twig or flower.

There are no aboveground symptoms, but a carrot root fly infestation can ruin your carrot crop, along with several other umbellifers. ​

The dibble, also known as a dibber, or a dibbler, was first carved from wood. The first dibble was probably nothing more than a pointed stick. To make it easier to use, the digging end was made pointier, and the handle end was rounded. 

During the Renaissance, dibbles were made from iron. Today, they are made from lightweight metals and plastics. I’m not a fan of plastics, but some of the hand-carved wooden dibbles are nothing less than works of art. You can also find high end stainless steel dibblers, if you like to spend your money that way. Many dibbles feature depth markings, to make it easier to plant seeds and bulbs at the proper depth.

Types of dibbles

Dibbles come in several different varieties: straight, T-handled, L-shaped, and trowel:

• The straight dibble was that early pointed stick. Over time, the straight dibble has evolved to incorporate a more comfortable, curved handle. Many straight dibbles have a pointed metal tip, for better penetration.
• T-handled dibbles use a crosspiece of wood as a handle, to provide a better grip and more control. The L-shaped dibble is similar to the T-shaped variety, but the handle only extends out in one direction.
• The trowel dibber combines a dibber with a trowel, with one tool on either end. These modern dibbles are generally made from aluminum.
• For the industrial strength gardener, there are now dibbles available that have a long handle and a foot powered poker. [Seems a bit extreme, in my opinion.]

Dibble boards

Dibbles can also be transformed into a board that creates the perfect spacing for seeds. These are easy to make from scrap wood and a dowel. Simply take a flat board, or a piece of plywood, and drill several, evenly-spaced holes in the wood. These holes should be just shy of the dowel’s diameter. Then, cut the dowel into pegs. These pegs will be the width of the board plus whatever planting depth you prefer, usually 1 inch. The pegs are tapped into the holes. You can glue them in place, or leave them somewhat moveable, to adjust the depth. If you're feeling crafty, you can add points to the digging end of end peg, but it isn't necessary

When starting seeds, simply press the dibble board against the soil for perfectly spaced seedlings. This reduces the amount of thinning you need to do later on. If you need to space plants out more, simply skip holes.

The down-side to using dibblers, especially in heavy clay soil, is that the surrounding soil is somewhat compressed by the pressure applied to make the hole. If the soil lacks organic material, this can make it difficult for young roots to take hold. As long as you aren’t pressing really hard, and your soil is relatively loose to begin with, this shouldn’t cause any problems. Dibblers are best used in planting trays filled with potting soil.

Lemon fruits

Lemons are a type of fruit called hesperidium. Hesperidium are berries with a leathery skin and fruit that forms in sections, called carpels. Within each carpel are hundreds of juice-filled sacs, called vesicles. Lemons contain citric acid, which is what makes them taste sour. Lemons are only a little more sour than limes, but they can be almost twice as sour as grapefruits, with five times the bite found in orange juice.

The lemon tree

Lemon trees (Citrus limon) are evergreen, which means the leaves stay green all year. They do not, however, handle cold temperatures very well. Mature trees can handle occasional light frosts, but young trees need protection in temperatures below 45°F. Lemon leaves and fruit both have waxy coatings that reduce moisture loss. You can grow a lemon tree in a sunny spot in your yard, in a container, or even on a balcony. The blossoms smell heavenly!

Lemon varieties

Most grocery store lemons are ‘Eureka’ lemons. This variety is also known as ‘Four Seasons’ because of its continuous production. This is also the most commonly available variety as bare root stock. There is also a pink-skinned variety of ‘Eureka’ that features green and yellow variegated skin. Thinner skinned and seedless “Bonnie Brae’ is grown in San Diego County, CA. If you want to make your own limoncello (lemon liquor), you will want to plant a ‘ ‘Femminello St. Teresa’, also known as ‘Sorrento’ lemons.

Contrary to popular opinion, ‘Meyer’ lemons are actually a cross between citron and a mandarin/pomelo hybrid. Other lemons-that-are-not-lemons include:

• Flat lemons - a mandarin hybrid
• Ponderosa lemon - a citron and pomelo cross
• Rough lemon - a citron and mandarine cross; often used as root stock

Caring for a lemon tree

Lemon trees are relatively trouble free, when grown in an appropriate location. Lemon pruning is normally limited to the standards of removing dead, diseased, and crossing branches. You will also want to remove vertical water shoots. Lemon tree trunks and the upper surface of exposed branches benefit from whitewashing, to prevent sun scald. Regular feeding will help your lemon tree stay healthy and productive. Each of the dosages listed below should be divided into 2 or 3 separate feedings:
    1st year - 3 tablespoons of nitrogen per tree
    2nd year - 1/4 pound of nitrogen per tree
    3rd year - 1/2 pound nitrogen per tree
    4th year - 3/4 pound nitrogen per tree
    5th year and on - 1 pound nitrogen per tree

Understand that 1/4 pound of nitrogen is not the same thing as 1/4 pound of packaged fertilizer. Assume, for example, that your 5 pound bag of fertilizer has an NPK of 10-5-2. This means that out of the 5 pounds, 10% of the bag is nitrogen, 5% is phosphorus, and 2% is potassium. [The rest is filler.] This works out to 1/2 a pound of nitrogen, a 1/4 pound of phosphorus, and 1/10 of a pound of potassium. In all likelihood, your lemon tree will not need those other nutrients, so they are best left out of the equation (especially until after you get a soil test). An easier way to feed your lemon and other citrus trees is to use blood meal or ammonium sulfate.

Blood meal contains 13.25% nitrogen, 1% phosphorus, and 0.6% potassium. To equal one pound of nitrogen, you would need to apply 7-1/2 pounds of blood meal. Five pounds of ammonium sulfate will give you the same amount of nitrogen. Just remember that these feedings are totals for the year and that they should be spread out over three different feedings, ideally in April, June, and August. Lemon trees also benefit from a top dressing of aged compost.

Lemon pests and diseases

The biggest insect threat to your lemon tree (and lemon trees across the country) is the Asian citrus psyllid, which can infect your tree with a fatal disease called huanglongbing, or HLB, for short. Leaf miners will burrow tunnels in citrus leaves, but the damage is mostly cosmetic, unless it becomes extensive. Other lemon pests include aphids, katydids, citrus cutworms, several varieties of mites, mealybugs, glassy-winged sharpshooters, Fuller rose beetles, hoopla beetles, leafrollers, snails, thrips, whiteflies, and nematodes. Several varieties of scale insects are attracted to lemon trees, including, black scale, brown soft scale, California red scale, citricola scale, cottony cushion scale, and purple scale. Lemon tree diseases include alternaria rot, armillaria root rot, anthracnose, brown rot, citrus blast, exocortis, phytophthora-related diseases, and the Tristeza disease complex.

Like other citrus trees, many lemon trees will follow an abundant year with a year of reduced production. This does not mean that anything is wrong.

Lemons are very easy to grow and they can produce an astounding amount of fruit. Get yours today!

Melon flies could end up costing California farmers over $4.5 billion if they ever get a toe-hold in the state.

Melon flies (Bactrocera cucurbitae) are a type of fruit fly. Native to India and Asia, melon flies were first seen in Hawaii in the late 1800’s. They have now become a devastating pest on the Islands. Quarantine stations have worked long and hard to prevent this pest from entering the Continental U.S. The melon fly was first seen in California in 1956, and several other times since, but whenever melon flies are identified stateside, eradication programs immediately go into affect. These programs use pheromones to attract male melon flies. These males are then sterilized and released. This messes up melon fly breeding. So far, this method has been effective. So, why would a gardener care, if the pest isn’t even here? Because maybe it is.

Lovage tastes like a cross between parsley and celery, but it can grow to over 8 feet tall!

Lovage grows best in full sun to partial shade and it needs soil with plenty of organic matter. You can help your lovage plant thrive by top dressing the planting area ahead of time with aged compost. As the growing season nears the end, you can allow flowers to produce seeds for future crops. In cold regions, the root is dug up and stored where it will be protected from freezing until the next spring.

Lovage has very few pest or disease problems. Leaf miners can cause cosmetic damage, but that’s about it. Because of its rugged demeanor and its celery-like flavor, lovage is an excellent addition to foodscapes in USDA Hardiness Zones 3-9.

White mold, also known as lettuce drop, tomato timber rot, and Sclerotinia stem and crown rot, is a collection of infections that can affect several garden plants. And they kill

Crown rot is also known as white mold in some regions, but that is something else entirely.

As damaged tissue dies and dries up, it will turn white and look bleached. Tiny (0.25–0.5 inch) irregularly shaped black flecks called sclerotia can be seen on and inside dead stems. Sclerotia are the resting body of the fungi, made up of a cluster of hyphal threads. These structures can remain dormant for a surprisingly long time.

White mold host plants

Along with lettuce and tomatoes, the legume, nightshade, and cabbage family members are susceptible to white mold. Other broad-leafed plants and many weeds can also become infected.

How to avoid white mold in the garden

Since prolonged moisture is needed for this fungus to come among us [sorry, I couldn’t resist], keeping things dry is a good defensive plan. These specific steps can help you avoid a white mold problem in your garden:

• Use raised beds.
• Avoid overhead watering.
• Space plants in such a way as to provide good airflow.
• Apply only as much nitrogen as is needed.
• Inspect senescent flowers and leaves for signs of infection.
• Remove and dispose of infected plants immediately.
• Monitor plants closely after 60°F to 70°F days with high relative humidity (95–100%).
• Inspect nearby ornamental plants and weeds for signs of infection.
• Employ crop rotation with non-host plants.

Severe infestations may require fungicides or soil solarization.

As prevalent as white mold is, it’s a good idea to know what to look for ahead of time.

Johnson spot is a fungal disease in rice, wheat, barley, rye, and millet. It also attacks your lawn.

Other names for this disease include rice blast fungus, pitting disease, and ryegrass blast. As a threat to your lawn, Johnson spot can infect kikuyugrass, fescues, ryegrasses, and St. Augustine grass.

How to prevent and control Johnson spot

Moisture is the key ingredient to this fungal growth. If leaves are wet and temperatures are between 77 and 82°F, Johnson spot can quickly take hold. Use these tips to prevent Johnson spot:

• Select resistant plant varieties.
• Space plants for good airflow.
• Avoid overhead watering.
• Water early in the day.
• Allow the soil to dry out between waterings (without causing water stress).
• Apply the minimum amount of nitrogen needed.
• Employ crop rotation.
• Dispose of infected plants in the trash, not the compost pile.

The Johnson spot fungus is resistant to chemical treatments, so these cultural practices are your only option.

Johnson spot is the most significant disease of rice in the world. Experts estimate that this disease destroys enough rice to feed 60 million people annually.

How to grow greengages

Unlike most modern fruits, greengages grow true from seed. This means, if you can find one, you can plant a tree of your own. The original cultivar, now called Reine Claude Verte, remains nearly unchanged from its ancestor. Not all greengages are self-fertile, so you may need to plant two trees to get fruit, depending on the variety. You can grow greengages outside in USDA Hardiness Zones 5-9. Like other plums, greengages love our hot, California summers, and cool, moist winters. You can start a seed indoors any time of year, but bare root trees should be planted January through March. If you don’t have a lot of room, greengages can also be espaliered along a fence.

Caring for greengages

Greengages should be given nitrogen in spring and fall. Amounts vary, depending on tree age, health, and soil. Trees should be pruned while they are dormant, in winter, and again just after fruit is harvested. Thin fruits to 4 to 6 inches apart, for the best quality and to reduce the chances of pest damage or disease.

Greengage pests and disease

Aphids and scale insects are the most common plum pests. Brown rot and shot hole fungus are the most common diseases.

Fruit is ready for harvest June through October, depending on the variety. It is not uncommon to have a bumper crop year followed by a more sparse crop, similar to many citrus trees. They simply do not have the energy or resources to crank out huge crops every year.

See if you can make room for these delicious fruits in your foodscape!

Grub control

Since most grubs are root feeders, getting rid of them can help your edibles, ornamentals, and your lawn stay healthy. Hand picking is the most effective method. This means breaking up the soil and picking them up. Breaking up the soil also makes it easier for birds to get their share of those high protein snacks. As much as we would all love easy fixes, products such as diatomaceous earth and white milky spore are not your best choices against grubs. Diatomaceous earth, while it can kill grubs, will also kill off beneficial insects. White milky spore, frequently advertised as a great grub killer, is generally only effective against Japanese beetle larvae.

Beneficial nematodes can be used against grubs, but the timing must be exactly right for them to do their job. Soil temperatures must be above 60°F, making it the method of choice in summer and early fall, but completely ineffective in spring.

How do you know if you have a grub problem?

Brown patches and wilting can be caused by several factors. The easiest way to see if you have a grub problem is to conduct a drench test. To do this, fill a large watering can or bucket with 2 gallons of water and gently stir in 1/4 to 1/2 cup liquid dish detergent. Then, mark off an area, 3 feet square, with some string. Pour the soapy water evenly over this area. Within 10 minutes, you will see whatever insects are living in that particular piece of soil. If you have a problem, it will be obvious.

As a child, I would eat around the center core of my carrots, leaving the darker, sweeter core for last. I didn’t know it then, but that inner core is called the stele.

Vascular plants have both root and stem steles, but they didn't start out that way. Primitive steles were nothing more than a strand of xylem, surrounded by phloem. [Remember, water and minerals ‘rise up the xylem’ from the roots, and manufactures sugars ‘flow down the phloem’ from the leaves. In case you forgot.]

More modern steles may consist of vascular tissue, pith, and pericycle. Pith is the spongy material seen in the center of stems, and the pericycle is a thin layer of tissue between the xylem and the endodermis. There are two major types of stele: protostele and siphonostele.

Stele diseases

​Diseases of the stele include phytophthora root rot, verticillium wilt, black root rot, and crown rot. In each case, prolonged exposure to wet soil creates the conditions needed for pathogens to infect your plants. Maintaining good drainage and soil structure can help prevent these diseases.

So, why would you care what sort of stele your plants have? Besides sounding really smart, being able to look up information about what’s inside a plant stem can help you identify unknown plants.

​What's inside your stems?

With a name like tarantula hawk, you might expect to see some B-movie horror monster soaring out of the sky with eight legs, but the tarantula hawk is actually a spider wasp that hunts tarantulas. It also has one of the most painful stings of any insect in North America.

Tarantula hawk diet

Adult tarantula hawks are nectarivorous, which means they feed on nectar and ripe fruit. They feed primarily on the flowers of milkweed plants, and mesquite and western soapberry trees. In some cases, that fruit has become fermented and tarantula hawks can find flying difficult.

Imagine, if you will, a drunk tarantula hawk riding a terrified tarantula, buckaroo style. There may be a movie in there after all…

Did you know that tarantulas migrate each fall? Now you know.

California red scale is a citrus pest found throughout California, except in Coachella Valley, where an eradication program is in place. These insects may be tiny, but California red scale is a serious pest of citrus trees. And their range is expanding.

Like other armored scale insects, California red scale (Aonidiella aurantii) have piercing, filamentous mouthparts that are inserted into stems, fruit, and leaves, and suck life-giving sap from your tree. These particular scale insects prefer lemons, limes, Valencia and Navel oranges.

California red scale and yellow scale are almost indistinguishable to the untrained eye. Yellow scale (Aonidiella citrina) is less of a problem than red scale and is rarely found on mature wood, whereas red scale can be found anywhere on the tree. The two pests behave in very similar ways, with the California red scale being a far more problematic pest.

Red scale lifecycle

You will probably never see a tiny, flying male red scale. They live for about 6 hours and have only one purpose. The females, however, attach themselves to your citrus trees, where they feed on your tree and give birth to 100 to 150 crawlers. Two or three crawlers are born every day to each female. These crawlers leave to find their own feeding site. They can also be blown to nearby trees by the wind, or move from place to place by catching a ride on a bird in a practice known as phoresy - though I don’t know if they do it on purpose. Once they settle on a new location, both males and females begin to grow a waxy dome over themselves. Male covers are more elongated, while female covers are more rounded. Females molt two more times, while males molt under their first dome four times before taking to the air.

Damage caused by California red scale

Chlorosis, twig and branch dieback, fruit loss, and, in severe cases, tree death can all result from California red scale infestations. This damage most commonly occurs at the end of summer, when trees are water stressed and scale populations are at their peak.

How to control California red scale

Scale insects are naturally protected from pesticides. And California red scale has developed a resistance to many insecticides, so, unless you are a commercial farmer or city government, you do not have access to chemicals powerful enough to kill off California red scale. [And would you really want to spray that stuff on your food?] Keeping your trees healthy with regular, deep summer irrigation will reduce water stress. And avoiding the use of broad spectrum insecticides will allow natural predators to do their thing against scale populations. Parasitic wasps and several varieties of lady beetles can provide significant control of scale insects. ​

​Because ants, dust, and poor air flow all make it more difficult for these beneficial predators to find and catch their prey, be sure to prune for good air flow, wrap tree trunks with sticky barriers to block ants, and give your trees an occasional rinse with the hose during the dustier parts of summer. In winter, apply dormant oils.
​
The next time you go water your citrus trees, take a closer look to see if California red scale has made an appearance.

Beans are easy to grow, help improve soil structure, and add nitrogen to the ground. They can also become infected with bean yellow mosaic.

Three different bean mosaic diseases commonly occur in North America: bean common mosaic, cucumber mosaic, and bean yellow mosaic. These are all viral diseases that cause downward cupping and wrinkling of leaves, especially as leaves get older, along with the telltale mosaic pattern. Bean leaves that develop a bright yellow mosaic pattern may have bean yellow mosaic virus. There are several strains of bean yellow mosaic (BYM). In addition to beans, bean yellow mosaic can infect peas, peanuts, soybeans, black locust, and fenugreek.

Bean yellow mosaic symptoms

You can differentiate between bean yellow and the other mosaic infections because bean yellow has a yellow mosaic rather than a light or dark green mosaic. Bean yellow mosaic also exhibits bright yellow spots on leaves. Plants infected at an early stage of development can become severely stunted. Remove them from the garden and toss them in the trash.

Bean yellow mosaic lifecycle

The bean yellow mosaic virus, or BYMV, commonly overwinters in legumes, such as alfalfa, clovers, fava beans, gladiolus, and vetch. The virus moves from plant to plant in aphids. When an aphid feeds on an infected plant, it becomes a carrier, transporting the disease to every plant it feeds on from that point forward.

Since resistant cultivars are not yet available, these tips may help prevent bean yellow mosaic in your garden:

• Buy certified disease-free seeds from reputable suppliers. [Do not use grocery store dried beans!]
• Avoid using broad-spectrum insecticides that kill aphid predators.
• Start seeds earlier, allowing them to reach the flowering stage before aphids become problematic.
• Treat heavy aphid populations with insecticidal soap or neem oil.
• Plant different legume crops as far away from each other as possible.
• Remove legume weeds from the area.
• Reflective mulches may reduce the number of aphids attracted to your plants.

Finally, if you see an infected plant, trash it.

Beneficial biter

Despite their bite, insidious flower bugs really are beneficial. They feed heavily on thrips [their favorite food], corn earworm eggs, mites, spider mites, small caterpillars, bollworms, whiteflies, scale insects, European corn borers, armyworms, potato leafhoppers, and a slew of aphid varieties, including spotted tobacco aphids, corn leaf aphids, and potato aphids. Insidious flower bugs are so beneficial, that they are raised commercially as a biological control against thrips, European red mites, twospotted spider mites, and most aphid varieties in eggplant, strawberry, cucumber, and sweet peppers crops. Research conducted in Florida found that insidious flower bugs were more effective at controlling thrips on sweet peppers than insecticides. Other research has demonstrated similar results with twospotted spider mites on bean plants, and soybean aphids on soybeans.

​Insidious flower bug description

These mixed blessings are small, only 1/5 of an inch long. They tend to be flattened, with an oval to triangular shape. They are black with white markings. Nymphs are yellowish-orange to brown, wingless, and teardrop shaped. If you look at an insidious flower bug under a microscope, you can see that they have piercing mouthparts, called beaks, which they use to repeatedly stab and suck the juices from their prey.

Orius insidiosus lifecycle 

​Insidious flower bugs seem to come out of the woodwork in late summer, though they have been around since they hatched, starting in spring. Eggs are laid in plant tissue, then hatch into nymphs, going through five instars before reaching adulthood. This takes approximately 20 days, and there can be several generations a year. Most of their diet consists of insects and insects eggs, but they occasionally eat plants and pollen when prey is scarce.

​Attracting insidious flower bugs

Despite the bite potential, these predators are good to have around. You can attract them to your garden by growing alfalfa, buckwheat, soybeans, cotton, grapes, and most deciduous fruits.

You can reduce the chances of getting bit by wearing dark clothing on hot days in late summer. For the most part, insect repellants do not work against these garden visitors.

Climbing plants use vines and tendrils to pull themselves ever upward, but they are not always strong enough to support a full sized pumpkin or watermelon. Providing extra support for heavy fruits can allow vines to become far more productive. Supporting fruit in hammocks also helps with pest control and frugal disease.

Growing up and saving space

If you are like me, growing melons and squash is an exercise in space-saving. Melons, pumpkins, cucumbers, watermelons, and cucamelons can all be grown up stock panels, in vertical gardens or towers, or up a fence. Left untrained, these long vines can take over an area. Cucumbers and cucamelons do not need extra support. In fact, cucumbers will grow in strange shapes if they come in contact with anything as they develop. Cucumbers are best allowed to hang naturally. But growing vertically puts a heavy strain on stems and tendrils as fruits get larger. That’s where hammocks come in.

Hammocks, insect control, and fungal disease

Raising fruit off the ground reduces the chance of many insect pests, such as darkling beetles, even finding your crop. At the same time, solid fabric hammocks can also create the perfect hiding spot for earwigs, so it’s a good idea to monitor your hammocks frequently, especially if you are using a closely woven cloth. Getting fruit off the ground also reduces fungal disease. Millions of fungi wait in the soil for just the right conditions - conditions that are created when a melon or pumpkin sits on the ground, creating shade and moisture collection. Great for fungi. Bad for your crop.

How to make melon (and pumpkin) hammocks

You can use an old pair of pantyhose, net onion bags, scraps of hardware cloth or chicken wire,  old dishtowels, or old T-shirts to create hammocks for your melons and pumpkins. I have tied strips of fabric around cyclone fencing, sunflower stalks, and stock panels. You can also slip colorful onion net bags over immature fruit and tie or thumbtack the bag to a fence, trellis, or other support. An added bonus to using onion bags - the colors make it easier to find your melons!

Get your melons and pumpkins up off the ground with hammocks!

Thorns, prickles, and other spiky bits

Thorns are a type of spinose structure made out of a modified leaf, stem, root, or bud. Many people use the terms bristles, prickles, spines, and thorns interchangeably. Botanically, these terms mean very different things:

• bristles - stiff plant hairs, or trichomes
• prickles - epidermis tissue anywhere on the plant, without vascular bundles (roses)
• spines - any part of leaf tissue that contains vascular bundles, such as the stipule or petiole
• thorns - modified stems, which may or may not be branched, and may or may not have leaves, and may or may not grown from a bud (citrus)

So, where bristles are stiff hairs and prickles are hard, spiked skin (neither of which contain plant veins), spines, being modified leaves, and thorns, modified stems, do contain plant veins.

Thorny problems

Plants use thorns as a mechanical defense against herbivores (and gardeners). Cacti are far less likely to be eaten when they are covered with hard thorns. And the pollinators who specialize in pollinating these particular types of plants seem to be unaffected by the presence of thorns. In some cases, thorns are also used to shade certain plant varieties, or to provide a layer of insulation.

Home, sweet thorn

Some thorns are hollow. These tiny chambers are called domatia. Plants, such as certain acacia species, produce domatium to provide shelter for beneficial arthropods (insects, spiders, and crustaceans). Similar to galls, which are produced by the resident, rather than the landlord, domatium are the plant’s side of a mutually beneficial relationship, most commonly with ants or mites. Occasionally, thrips may also move into these tiny apartments, but they are generally unhelpful to the plant. The plants that create these thorny thresholds are called myrmecophytes.

While I do not expect any of you to stop calling rose prickles thorns, why not impress your friends with your new-found knowledge?