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 doasges 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 is a perennial herbaceous plant that requires very little care. Stronger tasting than either celery or parsley, a little goes a long way, but all parts of the lovage plant make an excellent addition to soups, salads, casseroles, and stews, and the minced leaves take pasta and potatoes to new heights. Lovage seeds and stems are also used in candy-making.

White mold (Sclerotinia spp.) can remain dormant in the soil for a very long time. It takes a significant amount of cool moisture to wake one of these fungi up from its dormant sleep, but the underside of a head of lettuce, or a cabbage, provides just the sort of humidity needed to trigger an awakening and the ensuing infection. This disease is also known as Sclerotinia stem and crown rot and it is caused by two different fungi, depending on the host plant.

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
• irrigate to the side of plants, rather than directly on them
• space plants in such a way as to provide good air flow
• apply only as much nitrogen as is needed
• inspect senescent flowers and leaves for signs of infection
• remove and destroy infected plants immediately
• monitor plants closely after 60° 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
• in really bad cases, fungicides and soil solarization may be needed

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

How to prevent and control Johnson spot

Moisture is a key ingredient to this fungal growth. If leaves are wet and temperatures are between 77 and 82°F, Johnson spot can quickly take hold. To break this disease triangle, be sure to space plants in such a way that supports good air flow, avoid overhead watering, allow the soil to dry out between waterings (without causing water stress), and only apply the minimum amounts of nitrogen needed by the plants.


Of course, that advice is only partially useful when it comes to lawn care. To help your lawn avoid becoming infected with Johnson spot, water as early in the day as you can. This will allow plants to dry off before evening comes around.


This fungus has developed resistance to chemical treatments, so cultural practices are your only option. These practices include crop rotation, selecting resistant varieties, and disposing of infected plant material in the trash.


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 every year.

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, spending 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 in 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, which are not (yet) a real problem here, in California.


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.

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?

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.

Vedalia beetle diet

While the bright red variety most of us think of as ladybugs feeds heavily on aphids, vedalia beetles prefer cottony cushion scale insects. Adult vedalia beetles simply chew up their prey, while younger larvae pierce their victims and suck out their juices.


Vedalia lifecycle

Vedalia beetles start out as tiny red eggs. These eggs hatch out into tiny red larva. Vedalia larva start feeding right away and they go through several instars, or developmental stages, as they grow. They continue to feed until just before pupating. Then they attach themselves to a leaf as they prepare for their final transformation. [Unlike other insects that pupate, if you touch a healthy vedalia pupa, it should move.] One week later, an adult vedalia beetle emerges, ready to lay 100 to 200 eggs in its 1 to 3 month lifespan. ​

Combined with a parasitic wasp (Cryptochaetum iceryae), cottony cushion scale is now well under control in California, without the use of any chemicals. Since vedalia beetles are extremely sensitive to pesticides, it is a good idea to inspect an area for these beneficial insects before spraying chemicals.

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.

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.


Red scale lifecycle

You will probably never see a tiny, flying male red scale. They only 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 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 round. 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.

There are three different bean mosaic diseases that occur here in California: 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 be infected with the 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 as bright yellow spots on leaves. Plants infected at an early stage of development can become severely stunted and should be removed from the garden and tossed in the trash.


Bean yellow mosaic lifecycle

The bean yellow mosaic pathogen is called, very unimaginatively, bean yellow mosaic virus, or BYMV, for short. This poorly named virus commonly overwinters in legume crops, such as fava beans, alfalfa, clovers, and vetch, as well as in certain weeds and gladiolus. 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 disease-free seeds from reputable suppliers [Do not use grocery store dried beans!]
• avoid using broad spectrum insecticides that kill aphid predators
• start seeds early enough that they reach flowering stage before aphids become a problem
• heavy aphid populations can be treated 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.

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.

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?

Preventing and controlling pink root

Keeping plants healthy and employing crop rotation are the two best ways to avoid pink root from causing too many problems. A note on crop rotation: do not follow a cereal crop with onions, as it creates conditions that promote this particular pathogen. Severe infestations can be eliminated with soil solarization, but that’s a pretty drastic measure for the home gardener.


If you see pink, purple, or black shriveled roots on your onions, try growing them in a different area, in fresh soil, and be sure to feed, weed, and water them properly, and protect them from insects, to ensure that they stay healthy enough to protect themselves.

Symptoms of lower limb dieback

This disease normally appears in late April or May, on trees that are 7 or 8 years old. It starts out with the leaves on lower limbs yellowing, and then turning brown. Eventually, the entire branch becomes girdled by cankers and dies, right up to where it attaches to larger, scaffold branches, or the trunk. If you scrape the bark off of an affected limb, you will see brown spots in the wood. [Sorry, but I couldn't find an image I could use.]


Susceptible varieties

Some almond varieties are more susceptible to lower limb dieback than others. Padre almonds are the most likely to get this disease, with Butte being a close second. Almond varieties that show some resistance to lower limb dieback include Aldrich, Carmel, Fritz, Mission, NePlus Ultra, Nonpareil, Sonora, and Wood Colony. If you are shopping for an almond bare root tree, you might consider one of these more resilient varieties.


Preventing lower limb dieback

While research is currently underway, it is believed that overly wet soil, low light levels, and root exposure to herbicides or excessive fertilizer may weaken trees, making them vulnerable to whatever it is that causes this problem. This is just the opposite of shade tree decline, in which severe drought slowly kills a mature tree, with the early symptoms being a lack of leaf cover in the upper canopy, or crown, of the tree.


Lower limb dieback occurs most often in years with a cool, wet spring, followed by high temperatures. Soil compaction and low infiltration rates are also believed to play a role in lower leaf dieback. Trees with hull rot also appear to be more likely to develop this condition. In this case, fumaric acid and other toxins are believed to accumulate in larger branches when multiple spurs are infected. In this weakened state, these trees are also more likely to be infected by fungal opportunists, such as Botryosphaeria dothidea and Phomopsis amygdali. Phomopsis amygdali causes the stoma to stay open, desiccating the tree. Botryosphaeria dothidea causes cankers on a wide variety of plants.


Keeping your trees healthy is the best way to prevent lower limb dieback.  This means proper irrigation, reasonable applications of fertilizer (only after a soil test shows a need for it), and control of scale insects, which may play a role in the spread of this disease. Fixed copper, sulfur, and fungicide treatments have not been shown to be effective.

In addition to peanuts (Arachis hypogaea), South African bitter cress (Cardamine hirsuta) and the Genuflecting plant (Spigelia genuflexa) also use this unique method of reproduction.


Do you have any geocarpic plants in your garden?

You may be surprised to learn that potting soil is not really soil at all.


Potting soil, also known as potting mix and potting compost, has been used by gardeners since the 1800’s, and there are many good reasons for doing so. First, let’s find out what, exactly, is in potting soil.

Potting soil ingredients
​
Potting soil is a manmade recipe often made out of composted bark, sand, perlite, peat, recycled mushroom compost, and mineral nutrients. These mixes are treated to create the best pH for plant growth. Some potting mixes contain slow-release fertilizers. You can find potting soil that is rated ‘organic’ according to OMRI regulations, and you can find potting mix that includes ground up old car tires. It’s one of those cases where you really do get what you pay for. If you are committed to organic gardening, be sure to look for the OMRI label.


Potting soil’s unique properties

Potting soil is designed to retain moisture and nutrients. [Because of this ability, fungus gnats are often attracted to pots filled with potting soil - it’s the moisture.] Potting soil is also sterilized to kill off pathogens and weed seeds. This is what makes it so useful in container gardening. Some potting soil mixes are designed for specific plant species, such as African violets or cactus. Fresh potting soil is also what keeps your window sill garden and holiday plants healthy and productive. Stale potting soil… not so much.


How to recondition potting soil

Old potting soil may not actually contain anything useful to your plants. Like garden soil, nutrients are ultimately depleted and must be replaced. Also, potting soil, in particular, becomes hydrophobic as it ages. This means that it actively repels water, allowing it to quickly drain out of the bottom of the contain, leaching valuable nutrients as it goes. You can either dump it out and buy new potting soil, or you can recondition what you have. To recondition old potting soil, simply top dress it with aged compost and water it in. No digging or repotting needed. Also, you can apply an attractive mulch of wood chips on top of your potting soil to act as a slow release of organic material and some nutrients.


Uses for potting soil
​
Because of its ability to retain water and nutrients while providing ideal soil structure, potting soil is the best choice for seed starting, transplanting, and up-potting. The loose potting soil is gentle to traumatized root hairs and eases the transition. Potting soil is also the best choice for vertical gardening, tower gardening, and raised beds.

Native to China, Japan, and Korea, these invasive, wood boring beetles love to hitch overseas rides on wood-related packing materials: shavings, pallets, that sort of thing. In 1996, an infestation of Asian longhorned beetles (Anoplophora glabripennis) was discovered in Brooklyn. Two years later, a second sighting occurred in Chicago. Then, they were found in New York, New Jersey, and Illinois, where they are responsible for the removal of thousands of trees. These pests have already cost state and federal government (our tax dollars) over $168 million and that number looks to rise exponentially, now that they have expanded their range into California and Washington. 


​The potential economic impact was first estimated to be more than $41 billion. That number has increased to nearly $700 billion, and that’s before you factor in the damage to breakfast morale when the northeast’s sugar maples are attacked! Eradication efforts got into affect each time these invasive pests are found, sometimes successfully, sometimes not. The U.S. Customs Department is working hard to halt the importation of these pests. Eradication in the U.S. is still possible, but it’s an uphill battle. And they need our help.

Trees susceptible to ALB

Many popular hardwood trees are vulnerable to ALB infestation. These trees include alder, ash, beech, birch, boxelder, elm, hackberry, hornbeam, horse chestnut, mimosa, planes, poplar, sycamore, and willow. And blueberries! And members of the Prunus family, which includes apricots, peaches, nectarines, cherries, and almonds! We do not yet know what the impact will be on California’s native hardwood trees.


Experts predict that this pest could cause more damage than gypsy moths, Dutch elm disease, and chestnut blight combined, destroyed millions of acres of trees across the country, in parks, along streets, in backyards, and in agriculture. Dead and dying trees are more likely to cause fires and they are unable to support the biodiversity that keeps a region healthy. If you consider all the wood-based products we use every day, ALB could cause many prices to increase significantly. All because of an insect.


If you see it, catch it! Report it!

If you see an Asian longhorned beetle, catch it. Period. Just do it. They don't bite or sting. While they can fly, they don’t do it very well and only for short distances. You can do this.


Your efforts could save millions of trees and billions of dollars. Seriously.

​
Put your captive in a glass jar [they chew through trees, remember?] and place it in the freezer. Be sure to label the jar with where you found it (GPS position, if possible), the date you found it, and your contact information. These reports are critical if we are to protect our trees. Using this information, experts can create quarantine zones and implement eradication programs most effectively.


If you live in California, call the CDFA hotline at 1-800-491-1899. In fact, put the number in your phone now, so you’ll have it if you ever need it. I did. If you live outside of California, report it to your state’s Department of Agriculture. Together, we can save millions of trees.