Powdery Mildew

If there’s one grower’s gripe we hear lots about at Urban Garden HQ it’s Powdery Mildew.  So we asked our heavyweight in the pest control department, Zorro Torro, to lend some expert advice on what this nasty stuff is, what damage it causes your plants, and, most importantly, how to beat the crap out of it!

You’ll know powdery mildew has paid your plants a visit when it looks lot like confectioners’ sugar has been sprinkled on the plant leaves. At first it may be hard to spot as it might appear on just a small portion of the leaf appearing as an irregular circle. But it quickly spreads and soon appears on the surrounding vegetation. Soon the entire leaf is covered and at the same time colonies develop on the surrounding vegetation and in other areas of the garden.

So how does it all start?  Well, the plant becomes infected when an airborne spore, or conidia, lands on a leaf and germinates. It soon grows a guide tube that attaches tightly to the leaf. Then it pierces the plant cell wall and membrane and inserts a hollow tube that sucks up plant nutrients, weakening the leaf and slowing growth. Within a week the fungus produces tiny mushroom stalks that release millions of spores, ready to infect more leaf surfaces. The fungus also produces a secondary spore, which over-winters outdoors and may also hide in a greenhouse or indoor garden even after the crop has been harvested.

Powdery mildew is most likely to attack the young leaves, up to two or three weeks old.

A dozen or so different fungus fall under the heading of Powdery Mildew, but two different fungus species are the most likely culprits.  L. taurica, tends to attack warmer gardens. It prefers a temperature of about 77 °F (25 °C). S. macularisprefers a cooler temperature; however, the more virulent stain found in indoor gardens today  has adapted to tolerate more heat. Both strains thrive in moderate humidity and are not injured by water. Their conidia can live in water for short periods and are mobile in it. However, strong water sprays do destroy some conidia.



Powdery mildew is sensitive to heat. Neither species will grow at 90 °F (32 °C). and will quickly perish when above 100 ° F (38 °C).

To get a complete kill maintain the temperature for an hour. This may not be a feasible option in most indoor gardens for several reasons. The first is that it may be difficult to heat the space to such a high temperature. The second is that even a single peak of 100 ° F (38 °C) affects the growth of plants. Vegetative plants  with flowers or fruits in mid stage growth (weeks 3-7) may stretch a little from the experience. The heat treatment has relatively little effect on first and second week flowers or flowers nearing maturity.

You can minimize heat’s impact on plants in several ways. Heat the garden at the end of the day, as the lights are turned off. Since the plants are not photosynthesizing, they have lower water needs.

If the plants are being grown hydroponically, lower the temperature of the water to 60 degrees. Keeping the roots cool will help the upper plant parts beat the heat. It’s not difficult to do this, even if you don’t have a water chiller. Just add ice to the reservoir or flow through system. Roots of plants growing in soil can also be cooled using thermal ice packs at the base of the stem.

The heat treatment should kill off most of the fungus and its spores. The chances are there will still be some fungal re-growth. These can be eliminated using spot treatments.


If one particular plant seems to be infected with a few tiny white spots on a few of its leaves, get a bag large enough to drop the leaves into and then cut them off into the bag. Remove the bag from the room. This prevents spores, the white powder on top of the leaves, from becoming airborne while being removed. Remember to wash your hands and clean the scissors or knife with soap and water, hydrogen peroxide, alcohol or bleach.  Spray the plant with one of the sprays listed below after pruning to prevent re-infection and encourage healing.

If, you notice a re-infection a few days later, there is a good chance that this plant is very susceptible to powdery mildew and presents a good location for the infection to start and spread from. The plant should be removed immediately by placing a bag over it and removing it from the space. Then the space should be sprayed with one of the sprays listed below.


Here are some sprays that you can use to control the powdery mildew in your crop. All of these are safe to use for herb or for edible crops. Sprays are washed away by water, including rain.

Cinnamon Oil and Tea

Cinnamon is an effective destroyer of powdery mildew, with an effectiveness rate of 50-70%. It won’t kill it completely but it will keep it in check somewhat. It also potentiates other suppressive sprays so it is good to use in combination. To make your own, boil water, turn off the heat and add one ounce of ground cinnamon to one and a half pints water. Let the tea cool to room temperature. Add half a pint of 100 proof grain alcohol or rubbing alcohol and let sit. Strain the cinnamon. The spray is ready to use. A faster method is to add 2 teaspoons cinnamon oil to one pint of water and a dash of castile soap. Other herbs are also fungicidal. Clove, rosemary, and wintergreen oils are used in some botanical fungicides. The solution should consist of no more than 2% oil.


Garlic is antifungal and anti-bacterial and has several pathways for destroying fungi including its high sulfur content. It can also be added to other anti-fungal sprays.  Several garlic sprays are available commercially.

A homemade formula: Soak three ounces of crushed garlic in one ounce of neem or sesame oil and 100 proof or higher drinking alcohol or 70% or higher rubbing alcohol for a day or two. Strain. Then soak the garlic in a cup of water for a day. Strain. Mix the oil/alcohol, soaked water and 1 tablespoon liquid castile soap in a gallon container. Then fill with water and shake. The formula is ready to use.

A simpler brew consists of a teaspoon of garlic oil in a pint of water. To keep the oil and water mixed add a 1/8teaspoon of soap. Use garlic as a vaccination. Spray on new growth before there is a sign of infection.

Garlic is a general purpose insecticide as well as fungicide, so it should be used with caution on outdoor plants. It kills beneficial insects as well as plant pests.

Hydrogen Peroxide

Hydrogen peroxide (hp) is a contact fungicide that leaves no residue. It is an oxidized product of water and has an extra oxygen atom that is slightly negatively charged.  When it comes in contact with the fungi the oxygen atoms attach to molecules on the cell walls, oxidizing or “burning” them.

Household hp sold in drug stores has a concentration of 3%. Garden shops sell 10% hp. Zerotol® contains 27% hydrogen peroxide and an unstated amount of peroxyacetic acid. Together they have a more potent chemistry than hp, with an activity of about 40% hp. It is considered hazardous because it can cause skin burn similar to that caused by concentrated acids.

To treat plants with drug store grade 3% hp use 4 1/2 tablespoons and fill to make a pint of solution, or a quart of hp to 3 quarts of water.   With horticultural grade 10% hp use about 4 teaspoons per pint, 5 ounces per gallon. With Zerotol® use about 1 teaspoon per pint, 2 1/2 tablespoons per gallon.


Limonene is refined from the oil of citrus rinds. It has a pleasant citrus odor and is the active ingredient in many of the new cleaning products. It also has fungicidal qualities. I’ve used pure diluted limonene and it controlled powdery mildew, but did not eradicate it. Perhaps a higher concentration would have been more successful. Start using 0.5-1% limonene in water 1/2-1 teaspoon per pint.


Milk kills powdery mildew so well that both home and commercial rose growers all over the world have adopted it for their fungicidal sprays. Use one part milk to nine parts water. I’ve only used 1% milk, but other recipes call for either whole or skim milk and use up to 1 part in 5 milk. Some recipes add garlic or cinnamon to the mix. When using more than 30% milk, a benign mold is reported to grow on top of the leaves. Use a milk spray at the first sign of infection then protect the new growth weekly.


Messenger’s active ingredient is a naturally occurring protein called harpin that stimulates the plant’s own natural defense system. It has been proven to promote more vigorous hardier plants that are more resistant to disease and have increased yields. It is used to prevent infection and decrease its virulence

Neem Oil

Neem oil is pressed from the seed of the neem tree (Azadirachta indica), native to Southeast Asia, but now cultivated worldwide. Neem oil has low mammalian toxicity. It degrades rapidly once it is applied so it is safe for the environment including non-target species and beneficial insects.

Neem oil protects plants with its fungicidal properties: it disrupts the organism’s metabolism on contact, forms a barrier between the plant and the invading fungus, and it inhibits spore germination. It has translinear action, that is, it is absorbed by the leaf and moves around using the leaf’s circulatory system – it can also be used as a systemic. When it is applied to the irrigation water it is absorbed by the roots and delivered throughout the plant. Adding a 0.5% solution, about 1 teaspoon per quart, to the irrigation water will protect the plant from infection.

Neem oil is best used before the plant or the garden exhibits a major infection. By using it before powdery mildew appears, it prevents the spores from germinating. It should not be used on buds or flowers.

Oil Spray

Growers have used different oil sprays to prevent and cure fungal infections. Until recently most horticultural oil sprays were made from petroleum distillates. However, most organic growers have switched to using botanical oils. Aside from the safety factor botanicals such as cottonseed, jojoba, neem and sesame oils have fungicidal properties. They can be used in combination with other spray ingredients listed here. The oils are mixed at about 1-2% concentrations. A 1% solution is about a teaspoon per pint or 3 tablespoons per gallon. Add castile soap to help the ingredients mix. Oil sprays should only be used on the leaves, not the buds or flowers. Use weekly on new growth.

pH Up

pH-Up is a generic term for alkaline pH adjustors, used to increase water pH in indoor gardens. They come as either a powder or liquid. Its active ingredient is usually lye (KOH) or potash (K2CO3).

Fungi require an acidic environment to grow and die in alkaline environments. Changing the leaf surface environment from acidic to alkaline clears up the infection. An alkaline solution with a pH of 8 will make the environment inhospitable for the fungus and will stop its growth. This is one of the simplest means of controlling the fungus. It can be used on critically infected plants.

Potassium/Sodium Bicarbonate

Potassium bicarbonate (KHCO3) and Sodium bicarbonate (NaHCO3) are wettable powders that change the pH of the leaf surface toward alkaline.  Another reaction takes place; the fungus cell wall actually bursts in the presence of bicarbonate. Potassium is one of the macro-nutrients used by plants and therefore is preferred over sodium, as sodium can build up in the soil. Sodium bicarbonate can be found in your kitchen (baking soda), so some prefer it for ease of obtaining.  Both are more effective when used with an oil and spreader such as castile soap. They can be used to cure bad infections and prevents new ones.

Use one teaspoon of bicarbonate powder, a teaspoon of oil and a few drops of castile soap in a pint of water, or 3 tablespoons each potassium bicarbonate and oil and a half teaspoon soap in a gallon of water. Spray on new growth.

No Powdery Mildew™

No Powdery Mildew™ is a dual lysis action, 100% completely safe and effective powdery mildew eliminator. No Powdery Mildew™ actually attacks the powdery mildew spore right at the base/ mycelium, while infecting and destroying the cell pathogen completely. No Powdery Mildew™ then evaporates completely.   


Sulfur has been used to control powdery mildew for centuries. Sulfur sprays can be used indoors but they are not popular because of residue that remains on the plant. In greenhouses gardeners use sulfur vaporizers that heat elemental sulfur to the point of vaporization. The sulfur condenses on all surfaces including the leaves. A fine deposit of very low pH sulfur granules covers the leaf surfaces. The low pH environment inhibits fungal growth. The heaters use a 60 watt light bulb to heat sulfur which is held in a container above the light. The bulb supplies enough heat to evaporate the sulfur, but not enough for it to ignite. The problem with vaporizers is that they also leave a fine sulfur film on the leaves and flowers.

Active mildew: 7 to 8 hours per night 1 to 2 times a week.
Preventative maintenance: 4 to 5 hours once a week


Apple cider vinegar is toxic to powdery mildew because of its high acidity (low pH). Use it at the rate of 1 tablespoon per quart of water several times a week . Some gardeners recommend alternating using vinegar with potassium bicarbonate and milk.


  • Isolate all new plants in a separate area where they can’t infect other plants.
  • Filter incoming air to prevent spores from entering the room in the airstream.
  • Install a germicidal UVC light, like the ones used in food handling areas. The light is fatal to all airborne organisms passing through the appliance. This will kill powdery mildew spores that are airborne.
  • Spray the leaves with neem oil weekly. Neem oil presents both a physical barrier and a chemical deterrent.
  • Cinnamon oil and cinnamon tea can also be sprayed as a powdery mildew preventative. If you are using cinnamon oil use 1 part oil to 200 parts water. (1 teaspoon oil in a liter of water.)

Spider Mite Control

Description: Common across North America, many species of the spider mite (family: Tetranychidae) attack both indoor and outdoor gardens and can be very destructive in greenhouses. They live in colonies, mostly on the underside of leaves and feed by piercing leaf tissue and sucking up the plant fluids. Feeding marks show up as light dots on the leaves; as feeding continues, the leaves turn yellow, and may dry up and drop off. Spider mites are most common in hot, dry conditions and when their natural enemies have been killed off by insecticide use. They are also very prolific, which is why heavy infestations often build up unnoticed before plants begin to show damage. Large populations may be accompanied by fine webbing. Host plants are many and include strawberries, melons, beans, tomatoes, eggplant, ornamental flowers, trees and most houseplants.

Spider mites are not true insects, but are classed as a type of arachnid, relatives of insects that also includes spiders, ticks, and scorpions. Adults are reddish brown or pale in color, oval-shaped, and very small (1/50 inch long) - about the size of the period at the end of this sentence. Immature stages resemble the adults except only smaller.

Life Cycle: Most spider mite species overwinter as eggs on the leaves and bark of host plants. In early spring, as temperatures warm, tiny six-legged larvae begin hatching and feed for a few days before seeking shelter where they molt into the first nymphal stage. Nymphs have eight-legs and pass through two more molts before becoming mature adults. After mating, females are capable of producing as many as 300 eggs over a couple of weeks. Hot, dry weather favors rapid development of these pests. During such conditions the time it takes to pass from egg to adult may occur in as little as 5 days. There are several overlapping generations per year.

Note: Dispersal over a wide area occurs when spider mites are carried on their webbing by the wind.

Control: If pests are found, pinch or prune off infested leaves or other plant parts. Use the Bug Blaster or wash plants with a strong stream of water to reduce pest numbers. Commercially available beneficial insects, such as ladybugs, lacewing, and predatory mites are important natural enemies. For best results, make releases when pest levels are low to medium. If populations are high, use a least-toxic, short-lived natural pesticide to establish control, then release predatory insects to maintain control. Insecticidal soap or botanical insecticides can be used to spot treat heavily infested areas. Horticultural oils should be applied early in the season or late in the fall to destroy overwintering eggs.

Tip: Control strategies must take into account the fast development time of this pest, especially during warm weather when eggs are laid continuously. Just targeting the adults will do little good - repeat treatments are almost always necessary.

(Source: greenwaynutrients.com)

Foliage Spray Boosts Your Garden’s Health and Productivity

By Peter Donelan 
May/June 1988

As I wind my way down to our California hillside garden, I stop for a moment and examine a gray strand of Spanish moss that hangs from an oak branch over the path. This strange growth is not really a moss, nor is it a parasite leeching off its woody host. Instead, it’s a plant without roots; one that feeds solely by absorbing nutrients dissolved in fog or rainwater through its clusters of threadlike stems.

Of course, our normal house and garden plants do have well-developed root systems for gathering nutrients from soil. Yet, like Spanish moss, they also have the capacity to feed through above ground surfaces. Stems, buds, twigs and, most especially, leaves will readily absorb nutrients that are applied in a solution. So, in a real sense, leaves are roots in the air.

Foliar feeding is the practice of applying liquid fertilizers to plant leaves. This relatively new idea is fast becoming widespread. I recently worked at an organic research garden and minifarm. We relied on the soil’s microbial activity to supply crop nutrients, but that process was slowed by the area’s long, cool springs. So we began foliage spray feeding to stimulate plant growth early in the growing season.

The technique has many other applications. Some market gardeners now spray nutrients on fruit-setting crops like tomatoes and cucumbers to increase yields and on such leafy greens as lettuce and spinach to speed maturity and increase storage life. European grape growers use foliar feeds in their vineyards, and Chinese farmers similarly treat heading grain crops to increase yields. In our country, turf managers spray golf courses to help grass green rapidly, and some large commercial farmers use foliar feeds to prevent frost and drought damage. Other farmers spray regularly with liquid kelp to reduce aphid and red spider mite attacks or to control botrytis on strawberries and powdery mildew on rutabagas.

Fast Action  

Leaves are green factories where the complex chemical processes of photosynthesis produce the compounds plants need for growth. Foliar fertilizers are absorbed right at the site where they will be used, so they are quite fast acting. Some gardeners have actually seen plants improve within an hour of spraying.

Leaf sprays are also highly efficient fertilizers. Agricultural scientist S.H. Witter pioneered some of the first scientific studies into nonroot plant feeding in the early 1950s at Michigan State University. He found that the uptake of various plant foods was from 100% to 900% more effective when the nutrients were applied to the leaves instead of to the soil. Much soil fertilizer may never get used by plants. Water-soluble nutrients like nitrogen often wash out of the earth. (As much as 50% of the chemical nitrogen fertilizer used in this country leaches into our waterways—creating a complex of environmental problems.) Other nutrients may, through chemical reactions, be bound into a form unavailable to plants. For instance, 80% of the phosphorus applied through conventional fertilizers may get locked up in the soil. On the other hand, up to 80% of foliar-added phosphorus can be directly absorbed by the plants.

Before you rush out and put your garden on a daily leaf spray schedule, stop and remember the basic tenet of organic agriculture: Feed the soil, not the plant. Many feel that the biggest mistake of modern chemical agriculture has been its lack of focus on the sustainable base of all the earth’s production—the soil.

A healthy soil ecosystem rich in life and organic matter will help prevent nutrient loss due to leaching and chemical binding. It will even hold excess nutrients in storage until they are needed. For example, vesiculararbuscular mycorrhizae, fungi present in healthy live soil, increase the uptake of many nutrients, including phosphorus, and stimulate the growth of other beneficial soil microorganisms (such as nitrogen-fixing bacteria).

Fertilizers do not create fertility; building the soil does. In the long run, adding balanced, aged organic matter to your soil is the most efficient way to improve a garden. Foliar feeding, then, is best used as a supplement—a temporary or special procedure to boost production or help plants in a difficult growing situation.

The Trace Mineral Difference  

The supplemental role of foliar fertilizers helps explain why many leaf sprays are so low in the standard nitrogen-phosphorus-potassium (NPK) elements that make up conventional chemical fertilizers. Some skeptics feel anything so low in NPK can’t do any good, but proponents, like Lee Fryer of Food and Earth Services, argue that the variety of micronutrients in such foliar sprays is exactly what makes them effective.

Plants use some 50 mineral substances. Most are required in very minute quantities, yet a lack of any of these will have a profound impact on growth. As Liebig’s Law of the Minimum—a basic principle of plant science—points out, the nutrient in least supply is the one that limits plant growth.

Ocean products like seaweed, kelp and fish are common components of foliar fertilizers because they’re rich in micronutrients. These sea products also contain hormones and amino acids (cytokinins and betaines) that play essential parts in the plant growth process—they’re involved in cell division, as well as chlorophyll and protein production. Betaines are particularly useful in reducing plant stress during drought and in providing some resistance against marginal frosts.

When to Use Foliar Fertilizers  

Enough theory—let’s get to applications. Wait until young plants have enough leaf surface to absorb a spray well before you apply any foliar feed. Plants absorb foliar nutrients best in the early morning or late afternoon. Cloudy days are also good, but not if rain is imminent—it would wash the spray off the leaves. At what stage of growth should you spray? You can experiment with feeding at different stages, but the following are the ones most often recommended: during transplanting, flowering, fruit set and drought and cold periods, when sidedressing is normally recommended.

Leafy greens like lettuce or spinach: One application at transplanting, one (or two) three weeks later and one in the crop’s final week of growth.

Vining crops like melons or squash: Several applications when the vines start to run and the blossoms start to set, then one or two applications when the fruits are reaching full size.

Long-season fruiting crops like tomatoes, cucumbers, peppers and okra: One application at the first blossom set and then every 10 days or so during harvest.

Grains like wheat, corn, rye or rice: One application when the plant is 10 inches high and one or two when the heads or ears start to form.

Foliar Feed Recipes  

The first foliar sprays we used at our California research garden were made from weeds. Like sea products, weeds are rich in mineral nutrients. The “water composting” preparation process completely kills weeds and their seeds (even ones that might survive normal heat composting). Besides, turning a garden invader into a crop booster provides a pleasing irony.

To make foliar weed spray, fill a 30- to 50-gallon barrel with weeds and water, in a ratio of one pound of weeds to three or four gallons of water. After two or three weeks, the solution will be ready to use. Pour out as much as you need, filtering the liquid well so it won’t clog your sprayer. Then thoroughly wet your crop leaves. One gallon of the weed feed should treat approximately 100 square feet of plants.

You can add more water and weeds to keep the barrel filled. Or do the same process on a smaller, more concentrated scale with a five-gallon bucket. Pack the bucket with weeds and cover them with water. After a few weeks, filter out the liquid and dilute it by five to 10 times with water, and spray.

Seaweed and other foliar spray solutions are available from several garden companies. But to make your own, here are some other possibilities. Age, strain and use these just as you would foliar weed spray. Many of these brews give off a strong odor while they’re steeping. If that happens, float a layer of peat or straw on top to absorb the smell. Experiment with your own recipes, but remember that foliar feeds are always used in more dilute amounts than liquid soil fertilizers.

Compost spray: Combine one part mature compost with two parts water (by volume).

Rodale’s manure tea: Mix two cubic feet of manure with 60 gallons of water.

Lee Fryer’s basic spray: Combine ¼ pound of seaweed meal and ¾ pound offish meal with five gallons of water. Ferment one month, and dilute this five to 10 times before using.

Henry Doubleday’s skipper tea: Steep 10 pounds of kitchen waste in 10 gallons of water.

Rich weed spray: Soak 20 pounds of wilted comfrey, nettle or thistle in 20 gallons of water. Ferment one month. This very rich fertilizer should have close to the same NPK concentration as a commercial 10-10-10 fertilizer. For foliar use, dilute it five to 10 times with water.

Seafood spray: Place scrap fish in a barrel, barely cover with water, and let ferment for two or three months. Skim off the top layer of oil (compost the leavings), and use it diluted with water in a 1:80 ratio. You can store unused oil in a closed container.


Prove It  

Experiment for yourself. Regularly spray the leaves of part of a crop, but be sure to leave an untreated portion of that same crop as a control. That way you can honestly assess the effects of your foliar application. After all, foliar feeding is another task to add to that long list of gardening chores. If you spray nutrients only because this article recommends it, your enthusiasm for the job may diminish as soon as your recollection of these words does. But if you really see the difference in crops yourself, the noticeable improvement might guarantee foliar feeding a permanent place in your gardener’s heart.

Peter Donelan was a one-year gardening apprentice with John Jeavons’s Ecology Action of the Midpeninsula (Willits, CA). Jeavons is trying to help solve world hunger by developing gardening techniques for raising maximum food in minimal space. (His current indications are that a gardener may grow 322 pounds of food in six months on as little as 100 square feet.) Donelan is now teaching agricultural literacy at Stanford University. 

Foliar Feed Sprayers

A recycled (and thoroughly washed) window-cleaner bottle may be adequate for spraying houseplants, a small bed of herbs or an experimental half-row of tomatoes. But if you’re going to foliar feed a full garden, you’ll soon wish for a more sizable sprayer, one you can pressurize with a few pump strokes so it will mist continuously. MOTHER offered a design for a homebuilt two-liter sprayer back in issue 80. In addition, here are a few companies that offer sprayers (write for free catalogues):

Gardener’s Supply
Burlington, VT

A.M. Leonard
Piqua, OH

Pinetree Garden Seeds
New Gloucester, ME

Smith & Hawken
Mill Valley, CA

Stern’s Miracle-Gro
Port Washington, NY


(Source: greenwaynutrients.com)

Introducing Increase Grow™ and Increase Bloom™ the world’s first, 100% pure organic, co2 infused, complete, all in one plant food that delivers professional grade carbon dioxide directly to your plants leaf surfaces infused, primed and prefectly charged at 1800 PPM.

Introducing Increase Grow™ and Increase Bloom™’ trade secret formulation allows your plants to photosynthesize at a significantly greater rate. 

You Get What You Spray For Foliar Feeding

Foliar feeding, or the application of fertilizer minerals by spraying turf with a fertilizer solution, is a much talked about practice. Although superintendents have been practicing foliar feeding for years, there has been a frenzy about converting fertilizing greens solely with foliar fertilization, at the replacement of standard granular applications.

Whats all the hub-ub, Bub?

The foliar craze has come about. It’s for sure that the high shoot densities of these grasses require more surface cultivation to control thatch build-up, and smoothness. However, there is a tendency to say that these higher density greens grasses (both bentgrass and bermudagrass) need more fertilizer. Whether this is true or not, remains to be proven. Regardless, as part of an management scheme, it is desirable to avoid spikes of growth by applying small amounts of fertilizer on a frequent basis (spoon feeding) to grasses that grow aggressively and have high shoot densities.

It is often times easier to apply small amounts of fertilizer as a spray, rather than granular fertilizers (even greens grade materials). Also, there is no fertilizer pellets removed by mowing events. Note that you can still loose fertilizer from foliar feedings, if you don’t water in before mowing.

How does foliar feeding work for a plant?

The fertilizer elements applied to turfgrass leaves are absorbed through tiny cracks or pores in the surface of the leaf surface in the wax layer. These pores are very, very small tubes, and are lined with water. They are called transcuticular pores.

These pores are less than one nanometer in opening size (one billionth of a meter long). Because they are small, only small mineral particles can be taken in. Thus, small particles like urea nitrogen can enter, but not large particles like iron cheleates! These pore channels are also lined with negative channels, so they are attracted to positively charged fertilizer particles such as ammonium, potassium, magnesium and sodium, and tend to repel anions, like nitrate, phosphate, and sulphates. Likewise, nitrogen based on urea or ammonium can be transported through these leaf pores. These are the general rules.

Foliar fertilizer does not penetrate the stomates of leaves. The inner walls of the stomates (water control valves for leaf cooling) are covered with globs of wax, to repel outside water from entering the stomates, themselves. Also, foliar absorption is actually greatest at night (when stomates are closed). This shows that stomates play no role in foliar feeding.

The concentration of stomates on turf leaves does indirectly affect foliar-feed uptake. As the number of stomates increases, there are more micro pores appearing on the leaf between stomate cells. Under these conditions, the pores appear to be more permeable and numerous than other micro pore (cracks) on the leaf surface. These cracks (between the stomates) are larger in size and can allow passage of large size metal cheleates (like cheleated iron) and pesticides.

A curious observation is that foliar feeding always seemed to work better (for me) on cool season grasses, than bermuda! Well, cool season grasses have higher concentrations of stomates (to keep the leaves cool!). This makes sense and now I know why!

After the long journey and struggle to enter the leaf, nutrient uptake into cells is much like uptake within plant cell roots. Only now there is no restriction based on root condition. Therefore, foliar-feeding offers some advantage when root activity is limited for any reason.

There is some evidence that a certain percentage of foliar uptake of fertilizer requires plant energy. This occurs only when the fertilizer element is inside the plant, and moves from cell to cell.

As a process, foliar fertilization is not a plant efficient process! Leaf uptake of nutrients is only a tiny fraction of what is taken up in the soil solution by roots. This is why you still need to water in foliar-feed sprays, so they reach the roots. This is why spoon feeding requires lots of closely spaced foliar applications.

Likewise foliar applications sense since there is essentially no time lost due to soil water uptake via the root system. Ferrous sulphate applied as a foliar feed works well also, because the leaf uptake portion is quick. However, once washed in a large part of the iron from ferrous sulphate will be tied up in the soil because of our high soil pH conditions.

Likewise, urea applied as a foliar-feed will green up turf faster than when applied as a granular (or spray when watered in immediately).

Lastly, for the reasons explained above, periodic foliar-feeding has a great burn potential to the foliage. If you wanted to apply monthly fertilizer requirements in two spray applications, you would almost certainly burn the turf at some point. Fertigation is applying 30 days of fertilizer in 15-30 water applications! That’s the difference between foliar feeding and fertigation.
In summary:

1.Foliar-feeding works at the plant level by the entrance of preferred mineral elements through special pore or cracks in the waxy leaf surface layer.

2.The preferred elements for foliar-feeding include organic iron , urea nitrogen, ammonium nitrogen, potassium and magnesium. Increase Grow and Increase Bloom possess these elements that allow your plants to uptake nutrients more rapidly. 

3.Foliar applications of fertilizers are best applied as a mist for best results.

4.Since leaf penetration takes place better at night, apply a foliar feed spray during the day, let it sit, irrigate late in the A.M. morning hours, shortly before the morning mowing, when possible.

5.Credit when credit is due. Information from Dr. Richard Hull, Turfgrass Physiologist, University of Rhode Island.

(Source: greenwaynutrients.com)

Foliar Feeding Your Plants

Foliar feeding is a marvellous way of rapidly getting nutrient into a plant if you want to give it a quick boost or if it shows signs of a trace element deficiency. 

When a nutrient solution is sprayed onto a plant it is assimilated, whether it lands on the top or bottom of the leaf or on green stems. When the nutrient is in solution in water, the moisture is absorbed straight into the leaf via the leaf cuticle, through the stomata. Feeding through the leaves works more quickly than adding fertiliser to soil, which then has to be taken up through a plant’s root system. However, foliar feeding is not a substitute for root feeding.

Discolouration on leaves generally indicates that a plant is not getting the right quantities of trace elements in its nutrition. Peter notes a slight mottling on a shrub’s leaves which indicates a mineral deficiency. However, advice should be sought on determining the type of element deficiency present.

If the type of deficiency is known, the relevant element can be applied by spraying in a foliar feed solution. Beetroot are well-known for showing a boron deficiency when grown in soil which is alkaline and sandy. Half a teaspoonful of boron added to one litre of water will make a solution suitable for correcting this.

Any nutrient which can be dissolved in water can be used to foliar-feed, including magnesium, potash, nitrogen, iron, potassium, zinc or boron. Trace elements can be purchased from any nursery. Only use a very small amount dissolved in water and always follow the manufacturer’s directions.

Increase Grow™ and Increase Bloom™ is the most advanced, 100% pure organic foliar feeding nutrient regimen that is chalk full of nutrients which produce incredible results when used as a foliar feeding regimen.

A good time for spraying is during times of high humidity. The bonus is that for this kind of spraying, which does not use toxic chemicals, there is no need for protective gear.

Further Reference: Handreck, K., Gardening Down-Under: The Handbook For Inquiring Gardeners (CSIRO Publications, P.O. Box 89, East Melbourne, 3002, 1993)
Handreck, K. & Black, N.D., Growing Media For Ornamental Plants And Turf, (Sydney: University of NSW, 1994)

The Benefits Of Foliar Feeding

The Benefits Of Foliar Feeding
By Martin Capewell 

Ever since Dr. H.B. Tukey et.al back in the 1950’s, showed the true importance of foliar feeding of plant nutrients, it has been widely used in agriculture as a dramatic and fast way of getting nutrients into plants. Foliar feeding is not only useful for regular fertilizing to gain higher quality crops, but it is especially important for the correction of nutrient deficiencies and the addition of micronutrients. Dr Tukey’s research used radio-active phosphorous and radio-potassium to spray crops. They then measured with a Geiger counter, the absorption, movement and utilization of these and many other nutrients within plants. They compared the nutrient uptake at the roots from a soil application versus foliar spraying and found that a 95 percent efficiency of uptake compared to about a 10 percent efficiency from soil applications They also found the speed of absorption and use by foliar applications was immediate, whereas from soil applications absorption and plant usage was very very slow. Furthermore in soils that have a high pH or low pH, certain nutrients become unavailable for uptake into the plant in the soil. However with foliar spraying you can get the minerals into the plant until you make corrections to the soil. Foliar spraying also stimulates nutrient uptake from the soil. The leaves after spraying will generate more carbohydrates that it will transport down to the root and release as exudates. This will stimulate the microbial life in the soil and the microbes will thrive around the root mass making more nutrients available to the plant. Therefore it is a very good idea to use liquid fertilizers to supplement your nutrient programs to give your crops the optimum amount of nutrients it needs to get fast and efficient goodness into the plant so it can work harder to produce top quality food.

(Source: http)

Direct and Indirect Effects of Increased Carbon Dioxide on Plant Growth

San José State University

Thayer Watkins
Silicon Valley
& Tornado Alley

The Direct and Indirect Effects of Increased
Carbon Dioxide on Plant Growth

The direct effects of increased carbon dioxide (CO2) on plant growth refers to the change in plant grow with the levels of temperature, precipitation, evaporation and growing season at their present values. The indirect effects include the results of any changes in the other variables which affect plant growth that come as a result of the effect of increased CO2 on global climate.

Photosynthesis and the C3/C4 Plant Classification

Life is base upon chemical reactions; many, many chemical reactions; but the chains of chemical reactions known as photosynthesis are the basis in one way or another of all life. Photosynthesis involves the input of carbon dioxide and water with radiant energy and the presence of a catalyst calledchlorophyll. The outputs are carbohydrates and oxygen. The formal statement of the process is:

6CO2 + 6H2O + ν → C6H12O6 + 6O2

where ν represents photons of radiation.

The catalyst for the reaction, chlorophyll, is an organo-metallic compound containing magnesium. It is one of the three organo-metallic compoundswhich are the basis for life. The other two are the vital elements of the blood of mammals, hemoglobin, and of crustaceans, hemocyanin. Just as chlorophyll contains magnesium, hemoglobin contains iron and hemocyanin contains copper.

The process of photosynthesis is very complex and chemists could find little about the processes until radioactive isotopes became available. First, the radioactive isotope of oxygen, 18O, was used to create water, H2O. When plants were exposed to this radioactive water the radioactivity showed up in the oxygen exhaled from the plants. This showed that the oxygen created by plants comes from the water it uses rather than from the CO2. The oxygen in the CO2 gets incorporated in the carbohydrates created by the plants.

Second, a radioactive isotope of carbon, 14C, was used to create carbon dioxide. Plants were exposed to this radioactive CO2 for a few seconds and then the leaf material was chemically analyzed. In most plants the radioactive carbon showed in a compound called phosphoglyceric acid (PGA). The molecule of this compound contains three carbon atoms and one atom of phosphorus:

                           H   H   H
                           |   |   |
                        O- C - C - C -H
                        ||  |   |
                         O  O O-P-O
                            |   |                         
                            H   O-H

Most plants, including trees and flowering plants, produce PGA as the first step in photosynthesis. A few plant species, including tropical grasses such as sugar cane and corn (maize), produce malic acid or aspartic acid as the first step. The molecules of these compounds contain four carbon atoms and one nitrogen atom. The aspartic acid molecule is:

                              H H
                              | |
                              | |
                              H N-H

Because the initial products of photosynthesis for plants in this category involve compounds containing four carbon atoms this class is called C4. The other category of plants produces PGA which contains three carbon atoms so it is called C3. This classification is important because the responses of the two categories of plants to increased CO2 is different.

The Direct Effect of an Increase in CO2

Over the years there have been numerous laboratory experiments which conclude that increases levels of CO2 result in increased plant growth no matter how that plant growth is quantified. Sylvan Wittwer in Food, Climate and Carbon Dioxide tabulates the results. He observes

The effects of an enriched CO2 atmosphere on crop productivity, in large measure, as positive, leaving little doubt as the benefits for global food security …. Now, after more than a century, and with the confirmation of thousands of scientific reports, CO2 gives the most remarkable response of all nutrients in plant bulk, is usually in short supply, and is nearly always limiting for photosynthesis … The rising level of atmospheric CO2 is a universally free premium, gaining in magnitude with time, on which we can all reckon for the foreseeable future.

The quantification of the enhanced growth due to higher levels of CO2 has been given by H. Poorter in an article in the journal Vegetation:

Increased Growth
Resulting from a
100 Percent Increase
in the Level of CO2Plant

About 95 percent of all plants on Earth are of type C3. C4 plants constitute only 1 percent but the C4 crops of sugar cane, corn, sorghum and millet are economically significant. The other 4 percent of plants are not economically significant. They include desert plants such as cactus.

The Effect of Temperature on Plant
Response to Higher Levels of CO2

Photosynthesis consists of chemical reactions. Chemical reactions procede at a higher rate at higher temperatures. The rule of thumb is that there is a doubling of the reaction rate for every 10°F rise in temperature. Plants grow faster at a higher temperature providing they have adequate levels of CO2, water, sunlight and plant nutrients. The C4 plants have a great response rate for a higher temperature than does the C3 plants.

A higher temperature without adequate level of the necessary ingredients for growth might produce no response or even damage. Sylvan Wittwer, quoted above, states that under most circumstances the availability of CO2 is the factor which limits growth. Thus with a higher level of CO2 in the air plants can grow faster with a higher temperature.

Plants transpire water vapor to keep an even temperature. There are tiny holes on the underside of plant leaves, called somata, which are the openings through which the plant absorbs CO2. With higher level of CO2 concentration in the air the somata do not have to be open as wide. The narrower opening means that less water is transpired and thus less water is required by the plants. In other words, higher levels of CO2 increase the efficiency of water use by plants. This was confirmed in experiments reported by K.E. Idso and S.B. Idso. They found that enhanced CO2 increased growth by 31 percent in plants with adequate moisture but it increase growth by 62 percent for plants in moisture-stressed condition. In effect, enhanced CO2 by reducing water loss created the same effect as providing more water. Thus the effect in moisture-stressed plants was the effects of enhanced CO2 plus the effect of increased water.

The effect of increased CO2 in narrowing the stomata of plants has the additional benefit that a lesser amount of pollutants in the air will make it through the narrower openings. Thus enhanced CO2 has the effect of protecting plants against damage from air pollutants such as ozone or sulfur dioxide.

The effect of enhanced CO2 is even greater for plants grown under low light conditions. The enhance growth is greater than 100 percent for a 100 percent increase in CO2. This compares to less than 50 percent for plants grown in normal light conditions.

The evidence that clinches the argument is that some greenhouse owner artificially elevate the CO2 level to triple what the level in the atmosphere is.

(To be continued.)

Sylvan H. Wittwer, “Flower power: rising carbon dioxide is great for plants”, Policy Review (Fall 1992), pp. 4-10. 
H. Poorter, “Interspecific variation in the growth response to an elevated and ambient CO2 concentration,” Vegetation (1993), pp. 77-97. 
Sylvan H. Wittwer, Food, Climate and Carbon Dioxide, CRC Press, Boca Raton, Fla., 1995.
Patrick J. Michaels and Robert C. Balling, Jr., The Satanic Gases: Clearing the Air about Global Warming, Cato Institute, Washington, D.C., 2000. 
Fred Pearce, “Global green belt,” New Scientist, (September 15, 2001), p.15.

Here is a great video from our friends at MonsterGardens.com, explaining best practices for application of our NoSpiderMites product.