Other countries have faced mosquito-borne diseases for thousands of years. Now it’s our turn. And before you dismiss the problem, understand that over 700,000,000 people get sick or die every year from mosquito borne diseases. That works out to one out of every seven people get sick or die because of mosquitos, making them the most dangerous living thing on our planet!


Disease-carrying mosquitoes

Mosquitoes are vectors of disease. A single mosquito bite can infect you with malaria, Chikungunya, dengue, yellow fever, West Nile virus, and now Zika. Our four-legged friends are not safe either. Mosquitos can carry dog heartworm (found in all 50 states) and encephalitis. Encephalitis takes many forms, depending on the virus being transmitted and the host. Encephalitis can infect horses, birds and people and may lead to seizures, coma and death.


Mosquito borne disease are increasing exponentially in the United States. This is partly due to travel to and from infected areas. Once an infected individual returns home, all it takes is one mosquito bite to start spreading the disease. As gardeners, we spend more time outside than many other people, increasing our risk of exposure. Another reason for the increase is that viruses are becoming pesticide resistant.


So, what’s up with this Zika virus?

Until 2015, Zika was only found in Africa. At the time of this writing, the Zika virus was found in 20 countries, including the U.S. Less than one year later (December 2016), that number had reached 78. The Zika virus causes fever, joint pain, a rash, and your eyes turn red. It can also lead to Guillain-Barre syndrome, which causes muscle weakness and paralysis. That’s if you’re lucky and not pregnant; an estimated 46% of all Zika virus infections of pregnant women has caused severe birth defects or fetal death.


There is no vaccine for the Zika virus and the CDC expects the number of infections to escalate.


Unlike most mosquitos, which tend to feed in the evening, mosquitos that carry the Zika virus are aggressive daytime feeders. They can be found indoors, too! The Asian tiger mosquito (Aedes albopictus) and the yellow fever mosquito (Aedes aegypti, above) have black-and-white stripes and are half the size of normal mosquitoes.


Gardening in the presence of mosquitos requires some care. Use these tips to help prevent infection by the Zika virus and other mosquito-borne diseases:

• Wear long sleeves, long pants, socks and closed toe shoes and use light colored fabric
• Apply an insect repellant* that contains deet, picaridin, lemon eucalyptus, or IR3535
• Keep your screens** closed and repaired at all times
• Eliminate breeding grounds (pot saucers, flower vases, buckets, clogged rain gutters, old tires, wet sinks & shower stalls)
• Replace standing water in birdbaths and wading pools at least once a week
• Use mosquito dunks in ponds, birdbaths and fountains

It might sound like it’s more trouble than its worth, but it’s not. Simply storing unused flower pots and pot saucers upside-down can prevent a life-threatening disease.


Get out in the garden, but do it safely!


UPDATE (July 22, 2016): The Zika virus has now been found in Culexquinquefasciatus mosquitoes. The Culex mosquito is far more common than species previously found carrying the disease. This means all mosquitoes should be treated as potential carriers (unless you're an entomologist with excellent eyesight). 

*Research has shown that repellants made from citronella and lemongrass do not work (Consumer Reports)
** Window screens, introduced in the 1880s, were called "the most humane contribution the 19th century made to the preservation of sanity and good temper.” (Wikipedia)

Have the pea plants in your garden turned white?


If you look at the photo below, you will see that new (uninfected) growth is bright green, as it should be. Everything else on the plant looks bleached. That bleaching is caused by a fungal disease known as Fusarium wilt.

Similar to Verticillium wilt, Fusarium wilt is a common vascular disease in which a fungus (Fusarium oxysporum) clogs vascular vessels. It’s pretty much the coronary artery disease of the plant world. In addition to bleaching, common symptoms of Fusarium wilt include chlorosis, stunting, damping-off, brown veins, necrosis, and premature leaf drop.


This soil pathogen is found worldwide and it is spread by water splash, tools, and infected seeds and transplants. Fusarium wilt enters a healthy plant when germinating spores (mycelia) stab at the plant’s root tips and any damaged root tissue. That’s where the really amazing stuff starts to happen!


The Fusarium oxysporum fungus has no known sexual stage. Instead, it produces three different asexual spores: microconidia, macroconidia, and chlamydospores. Basically, the germinating spores (mycelia) inject themselves into a plant’s root system. From there, the mycelia move through the cells of the root cortex and into the xylem (a plant vein). Then, it starts producing the microconidia (asexual spores). The microconidia join the sap stream for a free ride to the rest of the plant. Eventually, there are so many microconidia that a vein is blocked. That’s when they germinate.


The vein blockage stops the plant form absorbing and moving nutrients, so the stomas close, the leaves wilt, everything looks bleached and it dies. As the plant dies, the fungus spreads throughout the plant and sporulates. [Cool word, right? It means “to produce spores”]


Fusarium wilt attacks a variety of garden plants and the pathogens are specialized according to the victim. Fusarium wilt can attack peas, beans, and other legumes, tomatoes, tobacco, sweet potatoes, cucumber and other cucurbits, and even banana trees!


Once a plant is infected with Fusarium wilt, there is nothing to be done except remove the plant and toss it in the trash. Planting resistant varieties in the garden can help prevent Fusarium wilt, and crop rotation is not an effective control method. This is because the chlamydospores can hang out in the soil for a long time. Some fungicides can be marginally effective. 


Since Fusarium oxysporum prefers heavy, moist soil, aeration and adding compost to the garden can bring more oxygen into the soil. This reduces the welcome mat effect for many types of fungus. Ensuring proper drainage is the best way to avoid this garden menace.

Fungicides are chemicals or organisms that kill or inhibit fungi and fungal spores. Since fungal diseases are responsible for more agricultural losses than any other cause, knowing how to fight these organisms is important.


Fungicides work in one of three ways:

• Direct contact - only works where it comes in contact with the plant
• Translaminar - absorbed through upper leaf surfaces and moved to lower surfaces
• Systemic - absorbed into the vascular bundle and moved throughout the plant in the xylem

Sulfur is a common component of most fungicides, as are neem, rosemary, and jojoba oil. Beneficial bacterium (Bacillus sabtilis) and fungus (Ulocladium oudemansii) are also added. Fungal plant diseases include:

• alternaria Blight (Early Blight)
• phytophthora blight (Late blight)
• cytospora canker
• nectar canker
• rust
  
• anthracnose (bird’s-eye spot)
• club root
• damping-off
  
• downy mildews
• powdery mildew
• galls
• leaf blister
• leaf curl
• leaf spots
• blackspot
• scabs
• smuts
• Fusarium wilt
• Verticillium wilt

Unlike most of these fungal diseases, Fusarium and Verticillium wilts cannot be controlled with fungicides.

While the use of fungicides can be effective, prevention is a better course of action. One way to reduce the chance of fungal infections is to plant resistant varieties. Another way to avoid fungal infestations is to improve air flow with good pruning, avoid watering from above, which may splash fungal spores onto nearby plants, and by removing and destroying any diseased plant tissue. Ensuring good drainage is another way to reduce the need for fungicides.

New growth is especially vulnerable to citrus blast, so it is a good idea to minimize fall and winter feeding and pruning to reduce winter growth in areas prone to citrus blast.

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Preventing citrus blast

Applying fixed copper or Bordeaux sprays before the first rain can reduce the likelihood of bacterial infection. They can also be used against fireblight, walnut blight, black spot on roses, peacock spot on olives, downy mildews and powdery mildew on grapes, and leaf curl, and shot hole on nectarines and peaches.


Bordeaux sprays consist of copper sulfate, lime, and water. You can make your own Bordeaux spray by combining 3-1/3 tablespoons of copper sulfate and 10 tablespoons of dry hydrated lime (calcium hydroxide) in one gallon of water. These materials are available at most garden centers. Avoid using slaked lime (calcium oxide) as it can burn your skin and eyes. Visit UC Davis Integrated Pest Management (IPM) for more detailed information. 

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Diseased twigs should be removed and thrown in the trash. As you prune out diseased areas, be sure to dip your tools in a 1 part bleach and 9 parts water solution to kill the pathogen and avoid spreading it to healthy plant tissue.


To prevent citrus blast, be sure to plant citrus trees with some wind protection and remove any dead or diseased twigs as soon as they are seen.

Atmospheric nitrogen is generally unavailable to plants, but they really need it. For nitrogen to be absorbed by plants it must be “fixed”. When lightening strikes the Earth, nitrogen is fixed, but the majority of fixation occurs via microorganisms called diazotrophs.


Diazotroph bacteria carry an enzyme that converts atmospheric nitrogen into ammonia, which is then converted into other organic compounds by the bacteria in a process called nitrification. Other microorganisms, such as mycorrhizae, carry similar enzymes that can also fix nitrogen into the soil. In exchange for their efforts, plants provide these bacteria with carbohydrates and sugars. The most effective nitrogen fixing bacteria are from the Rhizobium family. These nitrogen fixing bacteria are found in the root nodules of legumes, such as beans and peas. If your soil is low on nitrogen, it is a good idea to plant members of the legume family and let their microscopic nitrogen fixing factories get to work! 


Industrially, a method called the Haber-Bosch process uses heat and pressure to convert atmospheric nitrogen (N2) into 30% of the ammonium (NH4) used in agriculture. Since the agricultural revolution started 10,000 years ago, humans have been responsible for doubling the amount of nitrogen available to plants. The level of ammonia (NH3) has tripled and nitrous oxide (N20) has begun to break down our protective ozone layer. Rather than applying chemical fertilizers, there are other ways to improve the nitrogen cycle in your garden.


An excellent way to add valuable nitrogen to your soil is to raise or encourage worms in the garden. When worms poop, or die, the nitrogen released is available to plants through ammonification. Worms have the added advantage of improving soil structure, aeration and percolation. Without good soil structure, heavy rains can saturate the soil, creating a bog. In a bog environment, other bacteria step in and convert fixed nitrogen back into the unavailable atmospheric variety in a process called denitrification. 


Applying mulch and compost can also improve soil quality and structure. Mother Nature has evolved effective mechanisms for living things. We can best continue by following her example.

More common weeds (click on the picture to learn more)

Benefits of rain barrels

If you live in the Bay Area, you have probably noticed that our water is getting "harder". This is because of the minerals that are being dredged up from the bottom of reservoirs and ground water sources. It's not necessarily a bad thing (unless you are a coffeemaker or an iron), but it doesn't taste as good as it used to. Unlike the water that comes out of our faucets, rain water collected in rain barrels is free of chlorine and other chemicals used to make it potable. Watering container plants and in-ground plants with water from rain barrels means less potable water is being used. If you wash your hair from rain water, you may find that your hair feels softer.

Your average 2700 sq. ft. roof in the Bay Area can collect more than 25,000 gallons of water each year. Most rain barrels are significantly smaller than that, so you will only be able to collect so much before that water has to go someplace else, but it still ends up saving on your water bill.


The down side of rain barrels

As good as rain barrels are at conserving water, there are certain things you should know before you go shopping for your very own Amazing Rain Catcher. Here is what I have learned:

1. Sooner or later, your rain barrel will get full. If your rain barrel has an overflow outlet, you can connect a hose and redirect the water. If not, you will have to connect a hose to the spigot at the bottom and risk emptying the rain barrel and collecting nothing.
2. Rain barrels do not have any pressure besides gravity. This means that they tend to work slowly. The work better if they are raised up a little on a platform.
3. Rain barrels must be cleaned periodically. Roof grit, leaf debris, dust, bugs and who knows what else will collect in the bottom. Over time, that sludge can get thick enough to clog the spigot and it can become rather foul smelling.
4. Standing water in rain barrels can attract mosquitos, so be sure to create a barrier and use mosquito dunks and/or mosquitofish.
5. Some rain barrels (like mine) feature really pretty plant holders in the top. Before buying this particular style (or installing plants), ask yourself how you will tip the rain barrel over to clean it out with those plants up there.

Now, I’m not trying to discourage you. As I said, I have three rain barrels and I use them year round. In the peak of summer, if I have managed my 65-gallon rain barrels properly, they give me a total of 195 gallons of rain water to use on my plants that would have had to come from the taps.

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Let me know if you have any questions about rain barrels in the comments section. 

Structural support

Structural support, or anchor staking, prevents the root ball from moving while the new roots are established. Tree supports hold the young tree by tying it to 2-4 posts with straps. Do not use rope, wire, or hose segments, as these put too much pressure on a narrow area, risking bark damage. Straps spread the pressure out over a wider area, keeping the bark healthy and intact. Since your tree will being growing, be sure to keep the strap around the trunk loose.


Damage caused by tree supports

​Tree supports are only needed when a young tree cannot stand on its own or if it is being planted in an area with heavy winds. Also, tree supports should be removed as soon as they are not needed. Too many trees have become structurally unsound or vulnerable to pests or disease because the bark was allowed to grow over the support system. Don’t do this to your tree!


You may be surprised to learn that unnecessarily staking trees can actually hurt them in the long run. Plants grow in response to their environment. They lean toward sunlight and brace themselves against breezes, developing strength as they do so. This is called thigmomorphogenesis. Young trees that are prevented from developing this strength are more prone to breakage as they get bigger.


If you absolutely must provide tree support, it should be installed when the tree is planted, to avoid disturbing or damaging tender root systems. Tree supports should be placed one foot from the tree, with no branches touching.


There is a correct height for tree support ties. Too low and no support is given. Too high and the tree won’t learn how to stabilize itself. To determine the correct height, grasp the trunk of your floppy new tree and gently try to bend it over with the other hand. As you move your hand up the trunk, you will reach a point where the flop ends and the tree bounces back to an upright position. This is the magic spot. Your stakes should only be a few inches taller than this height to avoid damaging new branches as they come in.

After pruning the damaged limb to help it heal faster, I plucked the fruit and gave it a good wash before bringing it in, hoping it was ripe enough. By the way, citrus trees have wicked thorns! Be sure to use caution when working in or around them.


Citrus origins

There’s no mistaking the heavy, oily skin of citrus. This skin provides moisture holding protection from its subtropical origins. Hailing from Southeast Asia and Australian, modern citrus fruits evolved from small berries found on pummelo, citron and mandarin orange trees. Crossing these three ancestors in different ways has led to the creation of oranges, lemons, limes, grapefruit, tangelos, kumquats and dozens of other variations.


How to grow citrus

Citrus trees and shrubs grow easily in the Bay Area. They can be put in the ground or grown in containers. They prefer well drained soil and as much sun as you can provide. Since the fruit is very heavy, it is a good idea to protect them from heavy winds. Citrus trees can produce for 50-100 years, so use care when selecting a site. Be sure to feed and water your citrus regularly for maximum production. 


One-year old trees should be given 1/10 of a pound of nitrogen each year, while mature trees will need approximately 1-1/2 pounds. These amounts should be divided into three separate feedings in April, June, and August. If your trees are stressed by drought, you may want to spread those feedings out, using lighter amounts during the growing season, February through May. Blood meal is an excellent source of nitrogen, without all the fillers.


Watering citrus

Dumping too much water on your Navel Orange tree can leading to splitting. Split citrus are usually not ripe enough to eat but they provide the perfect breeding ground for bacteria, fungi, and other pests. Like mummies, they should be discarded as soon as they are seen.


Harvesting citrus

Knowing when to harvest your citrus can be tricky. Lemons and limes have distinct colors when they ripen, but Valencia oranges may still have a greenish tint to the skin when they are ripe. The only reliable way to tell if your fruit is ripe is to taste it. Unlike many other fruits, citrus does not continue ripening once they are removed from the tree. The best place to store your citrus is on the tree. If you do pick more fruit than you can use (or a branch breaks, dumping two dozen oranges in your basket), you can store them for 4-6 weeks in the refrigerator. You can also treat yourself with some fresh squeezed orange juice or a lemon drop! Personally, I grated the zest from two oranges over some sliced beef, juiced four oranges, and stirred in some corn starch, soy sauce, ginger and a pinch of Ghost Pepper for a delicious Spicy Orange Beef Stir-fry.


Citrus pests

Once established, citrus trees are pretty rugged. Here are some common citrus pests:

    •    Asian Citrus Psyllid (carries Huanglongbing Disease) 
    •    Leaf Miners
    •    Armored Scale & Soft Scale
    •    Aphids
    •    Leafrollers
    •    Mites
    •    Thrips


Citrus production

Citrus trees are heavy producers. A mature tree can produce up to 300 oranges a year. Do the math and that comes out to over 130 pounds of oranges! If you find yourself swimming in citrus, here are some fun uses for lemons:

    •    Remove fish smell from hands
    •    Neutralize alkalinity from masonry work or Burning Man gear
    •    Combine with salt to clean copper
    •    Apply to stains on fabric and leave in the sun
    •    Grind up peels in the garbage disposal for a fresh scent
    •    Rub lemon on mold and it disappears!
    •    Make your own invisible ink!


Do you have any good ideas for using citrus? Share them here!

Mummies in the garden?

But it isn't even Halloween!

If you have citrus, almond, apricot, apple, or other fruit or nut trees, then you’ve probably noticed brown, shriveled up fruits hanging from branches or splattered onto the ground. Mummification begins as one of several fungal infestations and it can occur in pretty much any fruit producing tree, shrub, or vine.

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There are many reasons for fruit mummification, but the important thing is to remove them quickly and completely. Fruit mummies are breeding grounds for billions of fungal spores that can wreck havoc on your current or next summer’s harvest.

Eutypa Dieback is a devastating fungal disease that attacks apricot trees and grape vines.

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While Ivory Tower nerds debate over the Latin name of the little fungi (depending on which plant it attacks and who you talk to), Eutypa Dieback is no joke. Also known as Dead Arm Disease, you won’t usually see symptoms until it’s too late.


In apricot trees, all of the leaves on an infected branch will wither and die, but remain attached to the tree. Oozing cankers are found along the lower branch and the bark turns darker than normal.


Two years after grape vines are infected with Eutypa Dieback, they will begin to display leaf cupping and distortion, chlorosis, and stunted new growth. If you take a cross section of the wood, you will discover V-shaped cankers.


This insidious microorganism works its way toward the trunk, killing the entire tree or vine. Also, the fungus responsible for Eutypa Dieback seems to be broadening its dietary preferences to include cherry, walnut, chokeberry, apple, almond, olive and pear, so it is critical that infected trees and vines be completely removed as soon as they are identified, to avoid spreading to healthy plants.

The bare branches of January make this an excellent time for pruning. 


Winter pruning helps improve the appearance and health of trees, shrubs, and roses. The only exception is apricot and cherry trees, which are susceptible to Eutypa Dieback. Apricot and cherry trees are best pruned in the dry months of summer.


Different plants have different pruning needs, but the overall goals are the same: a balanced structure, adequate airflow, and the retention of productive limbs. There are two types of pruning cuts: thinning and heading. Heading cuts control height, while thinning improves air flow and sun exposure. Keep in mind, while pruning, that new growth will head in the direction of the remaining buds.


The first goal of pruning is to remove dead, diseased or crossing branches. Dead and diseased limbs can allow pests and disease easy access into healthy tissue. Crossed branches will rub against each other, causing similar problems. You will also want to trim away branches that are angled too closely together and those that hang downward.


Structural pruning reduces the likelihood of uprooted trees falling on you or your house. Trees with too much weight to one side also risk splitting the trunk and killing the tree. Pruning early in the tree’s life can create a safer, more balanced structure. While the depth and spread of tree roots depends on a number of factors (soil composition, irrigation, variety and age of the tree, and more), pruning can help the root system keep your tree upright. To give you an idea of how much weight we are talking about: an average mature hardwood tree, with a circumference of 100” inches at chest height, weighs nearly 13,000 pounds! (Your average commuter car weighs 2,800 pounds - so imagine 4 or 5 cars hitting your roof in a storm to see why good pruning is so important) 


Pruning larger branches (those with a diameter of 2" or more), it is important to use multiple cuts to avoid peeling the bark beyond the final cut and damaging the remaining branch.

If you notice chlorosis on any of your plants, ask yourself the following questions:

• Is it getting enough sunlight?
• Am I over-watering? 
• Is the soil permeable?
• Does the soil provide adequate nutrients?
• Are any pests present?

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If the plant is being watered properly and getting enough sunlight, the problem is probably a mineral deficiency. The only way to really know what is in your soil is to send samples to a local, reputable lab.  Over-the-counter soil tests are generally a waste of money.


When I submitted soil samples to the Extension office, I learned that my soil has an abundance of every nutrient known to humankind, except iron.


Plants use iron to process nearly every other nutrient, so it is critical to healthy plants. Unlike nitrogen, which can move freely within a plant, once iron is absorbed, it stays where it is. You can add iron to the soil or, for faster results, you can apply foliar (leaf) sprays. Low levels of zinc or magnesium can also cause chlorosis, as can certain pathogens, the wrong pH, or compacted soil.
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As soon as your plant has adequate sunlight, the correct amount of water, healthy soil, and sufficient iron, its little energy factory will kick right in and everything should start greening up pretty quickly.

Crown rot symptoms

Signs of crown rot include rotted plant tissue at ground level, wilting, leaf drop, trunk discoloration and leaves that turn yellow or even red or purple. Established trees may ooze a dark sap around the infected area. Older plants may survive a few years, but young plants normally die quickly.


If crown rot is found in the garden, your best choice is to pull up the plant and discard it. In rare cases, a tree can be saved by pulling soil away from the trunk and cutting away diseased areas. Fungicides are ineffective in treating Crown Rot.


Preventing crown rot

Prevention is the best course of action in areas prone to crown rot. To reduce the likelihood of crown rot taking hold, use these preventative measures:

• Ensure proper drainage 
• Amend soil with organic matter and compost
• Plant trees properly, with grafting unions above ground  level
• Keep mulch at least 6” away from trunks
• Never allow sprinklers to spray tree trunks
• Rotate crops such as tomatoes each year

While we are all familiar with the pollinating power of honeybees, they are many other beneficials that pollinate, including wasps, flies, butterflies and moths, and even some beetles! As these beneficial insects move throughout the garden in search of pollen, nectar and prey, they carry sticky pollen from flower to flower, increasing garden production.


In addition to boosting the garden’s bounty, beneficial insects eat and/or parasitize insects that carry disease and devour crops. Parasitization occurs when a beneficial insect lays its eggs in the body of another insect. When the eggs hatch, the larva devour their host as a first meal. It’s brutal, but that’s how it works.


In our age of convenience and quick results, many gardeners turn to chemicals to rid themselves of bad insects. This is rarely a good idea. Chemical pesticides may kill indiscriminately, removing beneficials as well as bad bugs. Encouraging predator insects to take up residence in the garden can keep most bad bugs under control without any adverse effects to you or the garden.
                                     

The most common beneficial insects include:
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• Spiders (Aranae)
• Assassin Bugs (Reduviidae) 
• Praying Mantis (Mantodea)
• Damsel Bugs (Nabidae)
• Lacewings (Chrysopidae, Hemerobiidae)
• Wasps (Hymenoptera)
• Ground Beetles (Carabidae)
• Ant Lions (Myrmeleontide)
• Tachnid Flies (Tachinidae)
• Ladybird Beetles, Ladybugs (Coccinellidae)

                                                                                                

So, how can you attract and keep these bastions of beneficial bugs?

Many garden shops sell containers of beneficial insects, but this is generally a waste of money. If you do not provide the right habitat, they will leave for greener pastures. If you build it, however, they will come.


The following is a list of plants known to attract and maintain beneficial insects in the garden (From modern farmer):

     Spring-Flowering Beneficial Attracting Plants
          Sweet Alyssum (Lobularia maritima)
          Rosemary (Rosmarinus officianalis)
          Thyme (Thymus vulgaris)
          Crimson clover (Trifolium incarnatum)
          Bugleweed (Ajuga reptans)
     Early/Mid Summer-Flowering Plants
          Lavender (Lavandula spp.)
          Yarrow (Achillea millefolium)
          Mint (Mentha spp.)
          Queen Anne’s Lace (Daucus carota)
          Roman chamomile (Chamaemelum nobile)
     Late Summer/Fall-Flowering Plants
          Bee Balm (Monarda didmya)
          Mullein (Verbascum thapsus)
          Goldenrod (Solidago spp.)
          Fennel (Foeniculum vulgare)
          Aster (Aster chilensis)


Not only will these plants attract and maintain beneficial insects in the garden, but they also provide seasonal color and a few tidbits for the kitchen!

No, I’m not talking about Medieval medical practices!


​Leaching describes how water-soluble plant nutrients are washed away with rain and irrigation. 


While your plants certainly need water, too much of a good thing can be a bad thing. As nutrients are washed down from the topsoil and into the groundwater, they can cause contamination and algae blooms.


Our Bay Area clay soil holds far more water than sandy soils, but every soil has a carrying capacity. Once that limit is reached, gravity will pull the water downward into underground waterways where it will ultimately flow to lakes and oceans. As it flows away, the water carries nitrogen, salts, fertilizer, pesticides, fungicides and whatever else was in your soil with it - leading to a potentially dangerous chemical soup that can wreck environmental havoc. Leaching also moves valuable nutrients out of reach from your plants roots.

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To avoid leaching, it is always a good idea to water only as much as is needed. You can see for yourself where your irrigation water is going simply by digging a hole next to the plants you intended to water (but not too close). Many people are surprised to discover that the water intended for their tomato plants actually went in another direction due to hardpan, sandy pockets, or poor soil structure. Improving soil structure with compost can improve drainage and help prevent leaching.