What’s up everyone? Dr. NPK here.

Today’s post is about diagnosing some common secondary plant deficiencies and some potential remedies for them. It’s finally time to devote a blog post to my “doctor” status, right?

Seriously though, I’m not a medical doctor, so don’t listen to me in that realm. My doctorate is only in chemistry! Over the next few months, I’ll detail certain elements and how to fix their respective deficiencies in plants.

The jackpot for scientists is a well-designed experiment (Editor’s Note: Commonly referred to as a clinical study). Scientists are always trying to setup a system that tests one variable. In science, you can’t make a conclusion (or diagnose a culprit) unless you are rigorously testing for one variable only! I cannot stress this enough.

For example, let’s say your plants are not doing well. To fix the problem, you change the feeding timing for your plants as well as the quantity of fertilizer. The plants start to look better; you blame the amount of nutrients you were using. However, because you changed two variables (feeding time + amount), you cannot make a definitive conclusion! This is a common issues with growers.

To be clear, I don’t say this to scare you; I just want to make sure you understand that sometimes identifying the culprit is harder than you think, and that it is important to have an open mind that there may be multiple issues or variables at play.

Ever wonder why most calmag supplements contain both calcium and magnesium? Most formulators put these two vital nutrients together because it can be very difficult to diagnose one deficiency over the other. Also, calcium ions (Ca²⁺) and magnesium ions (Mg²⁺) typically behave the same way in your water solution; if you are getting nutrient lockout of one (e.g., calcium sulfate or calcium phosphate formation, the white salt at the bottom of your res), you are likely getting nutrient lockout of the other (magnesium sulfate is an exception, but magnesium phosphate is insoluble). Elite CalMag is our solution to blanketing any issues you may have with a lack of secondary nutrients. When I think of secondary nutrients, I think of chlorophyll, which are green. If I am deficient in any of these nutrients, my chlorophyll count will be low, and I would expect lack of green color.

Of the secondary nutrient deficiencies, calcium deficiencies tend to be more concerning, because calcium is also used in the growth of the plant’s cell wall. Things to look out for:

1. Yellowing at the top of the plant because calcium cannot migrate through the plant like other elements
2. Weak stems (poor cell wall = poor growth)
3. Slow growth (despite your main macronutrients being correct)

If you are sure you are supplementing with the correct amount of calcium (remember, if you use RO, use Elite CalMag), a common issue I see with growers is their root zone pH is off. Calcium uptake in cannabis plants is pH-dependent! You should target 5.2-6.1 pH range to ensure proper calcium uptake. An easy way to tell if your plant is uptaking calcium is to use one of your calcium supplements, and measure your EC before the roots (but after the sump) and then after the root zone. If your EC doesn’t go down, it means your plant hasn’t taken in any of the nutrients (likely the calcium). Lastly, check your reservoir for calcium lockout, which will appear as white solids in your reservoir. Usually these useless inorganic salts are formed when you mix the concentrates too quickly. Add each fertilizer product to your water reservoir more slowly with good mixing so it has time to fully dissolve before adding the next fertilizer concentrate.

Calcium deficiencies will typically appear in newer leaves. This is because calcium stored in older leaves cannot be transferred to new growth. Calcium is considered an “immobile” ion in the plant.

As I mentioned before, magnesium deficiencies follow similar appearances to calcium deficiencies (fewer chlorophyll, the whole brown/yellowing deal, etc). There’s one key difference between them: calcium-caused browning affects new growth from the beginning (and affects plants towards the top of the plant), magnesium-caused browning affects already-established leaves (e.g., they don’t “grow in yellow,”). Here are some magnesium deficiency signs to watch for:

1. Curling down of leaves
2. Yellow/browning of leaf tissue outside of the veins
3. General plant droopiness (not the most useful diagnostic, could be a variety of things)
4. Calcium deficiency symptoms that affect lower parts of the plant (unlike calcium, magnesium is a mobile ion in the plant).

Troubleshooting is similar to calcium deficiencies: check your EC before and after the root zone, look for nutrient lockout, confirm you’re in the right root zone pH (similar to calcium’s pH range) and make sure to supplement your RO water with Elite CalMag. Remember: magnesium deficiencies can be disguised as calcium deficiencies, so make sure to keep an open mind when troubleshooting!

Magnesium deficiencies will typically appear in older leaves. This is because magnesium is allocated to new growth as it is a mobile ion in the plant.

Calcium and magnesium are two vital elements to grow good bud. Yellowing is often a sign of an impact on chloroplasts/chlorophyll, and it’s a good chance it’s related to the secondary nutrients (including iron, which we will discuss in a later post). Using Elite CalMag could solve all your problems with a single supplement!

Resources:

Want to get in touch with Elite Garden Wholesale? They can be reached via the following methods:

1. Website: https://www.elitegardenwholesale.com/
2. Email: info@elitegardenwholesale.com

All growers know that plants need light, nutrients, and water to grow. But recent scientific advancements have revealed how soil microbes can take plant growth and health to the next level. It is increasingly clear that plants need beneficial microbes to maximize their phenotypic potential. Many growers are discovering the benefits of integrating microbial inoculants into their indoor and outdoor cultivation management practices.

Microbes are the basis for all life on Earth. Bacteria and fungi shaped our planet to create the very foundation upon which plants exist – from the carbon dioxide they breathe to the soils they grow in. About 700 million years ago, plants evolved into a rich microbial world. Their roots extended into soils already teeming with microbial life. Ancient plants quickly evolved to actively support their microbiomes by releasing sugars and other metabolites (called exudates) through their roots, which microbes eagerly use for food. In return, soil microbes break down dead plant material and recycle nutrients. In nature, all plants are surrounded by diverse communities of bacteria and fungi – different forms of microbes that we collectively call “the microbiome.”

In natural soils and well-nurtured agricultural fields, microbes are abundant and omnipresent. In a handful of healthy soil, there are billions of individual microbial cells. These cells represent tens of thousands of different bacterial and fungal species. Thousands of scientific publications have revealed the many ways in which soil microbes support plant growth. For example, by making nutrients more available for plant uptake, they maximize root growth, flowering, and bud production. Microbes also communicate with plants through chemical signaling pathways, helping plants respond to environmental stressors and thus preventing nutrient lock-out events. A healthy microbiome can trigger a plant’s immune system to fight diseases and create a barrier that inhibits pathogens.

In nature, plants are able to select particular microbes from the tens of thousands of species living near their roots in order to maximize their success. They engineer their microbiome through the chemistry and quantity of chemicals they release from their roots and through the timing and rate of nutrient uptake. However, managed agricultural and horticultural systems have much lower microbial diversity for the plants to choose from. As a result, plants are unable to optimize their microbiome without the deliberate addition of microbial inoculants.

Beneficial microbes are the key to unlocking a plant’s genetic potential to maximize yield and bring out each strain’s unique qualities. When deciding to use microbes in your cultivation practice, a good place to start is by trying to mimic key features of natural systems where plants and microbes work together in harmony. In nature, no microbe lives alone. Instead, microbes interact closely with each other, working in groups to perform complex functions like breaking down plant material to release nutrients. Each microbe completes a different step in the process and then performs a metabolic hand-off. This is analogous to assembly line workers that specialize in specific parts of a complex process. A healthy microbiome should contain groups of microbes (known as consortia) that work together to conduct critical functions.

Whether you grow hydroponically or in soil, indoors or outdoors, you can put the power of microbes to work. There are many ways to enhance your microbiome. Some growers produce their own compost teas – an inexpensive way to add living microbes to your system. There are also many commercially available microbial formulations that include one or more species of bacteria or fungi. Beneficial bacteria are most often inoculated into soils or hydroponic systems to promote plant growth by increasing plant nutrient uptake. One way bacteria accomplish this is by releasing enzymes into the soil or other growth media. Enzymes catalyze the breakdown of nutrient-rich molecules into plant-available forms. Soil bacteria can produce many different types of enzymes to cycle important macronutrients like nitrogen and phosphorus for plant uptake.

The incredible diversity of the microbial world was unknown prior to advancements in genomic techniques that have been made in the last few decades. We are now in the midst of a microbial revolution. Plants and microbes have been closely intertwined throughout evolutionary history. New microbial technologies and management practices are making it easier than ever for cannabis growers to harness the power of natural soil microbes and grow the most productive and healthy plants possible.

Resources:

Want to get in touch with person? They can be reached via the following methods:

1. Website: https://mammothmicrobes.com/
2. Email: info@growcentia.com
3. Phone: (970) 818-3321

Powdery mildew is a common fungal disease of angiosperms (basically, any plant but conifers). The growing fungus looks grayish white and powdery.

A powdery mildew infection.

Powdery mildew is an infection from one of the many fungal species of the family Erysiphaceae (ee-rhy-suh-facie). Powdery mildews generally live externally from their hosts, and not inside of them. In other words, they are ectoparasites, not endoparasites. This means that powdery mildew is not a systemic infection. It does not grow into parts of the plant or propagate internally throughout the plant.

Furthermore, powdery mildews’ parasitic process requires host cells to remain alive. They are what scientists call obligate biotrophic parasites. Biotrophic pathogens usually cause disease on only a relatively small group of host plants. This is because of the different genetics and molecular processes/structures required for wider ranging host-pathogen interactions.

Side Note: There’s a common misconception about the word “systemic”. Systemic fungicides can attack a non-systemic pest. After you spray a plant with the systemic fungicide, it moves throughout the plant. A systemic pest would also move throughout the plant, but PM is not a systemic pest.

The first symptoms of a powdery mildew infection are dusty gray or white spots on either side of the leaves. If left untreated, the growing fungus will produce spores and rapidly spread to other leaves, stems, and flowers. While powdery mildew doesn’t typically kill the host plant, it can cause early senescence and stunt the plant’s growth and development. Some plants may show local necrosis when badly infected.

The fungus can be transmitted by pests such as aphids, or via touch, tools, clothing, shoes, and even by airflow through previously contaminated spaces. These transmission methods are called “transmission vectors”, or sometimes simply referred to as vectors.

Potential transmission vectors.

Relative humidity plays an essential role in the control or spread of mold. Molds and fungi particularly like dry leaf surfaces and humid environments. For the best inherent protection during growth phase, relative humidity (RH) should be kept between 40% and 55%. Flowering requires drier conditions, with humidity levels between 25-45% RH.

Editor’s Note: Dewpoint is also a very useful tool for measuring the danger posed by fungi. Ideally you want to avoid any liquid water in the environment. Check out this dewpoint calculator to see how the dewpoint affects mold risk.

One very critical thing to monitor is the night time RH level. The night time RH often spikes and can lead to condensation. Wide RH swings are conducive to powdery mildew infection.

Additionally, crowding your plants can produce pockets of stagnant, high humidity air, so called “microclimates,” so give your girls some room. It’s a good idea to keep the lower fan leaves trimmed to prevent these microclimates.

Dedicated shoes, shoe covers, or a boot bath, and hand washing (alcohol based hand sanitizers are good) before entering the grow area are your first line of defense. It’s also a good idea to not wear your outdoor clothes into your grow.

Clean and sanitize tools and equipment that come into contact with multiple plants. Immersing tools for a couple minutes in a sanitizing solution prevents cross contamination with healthy plants. A pint of household bleach mixed with a gallon with tap water will work well. Use this sanitizer solution to spray pots, plant trays, water tanks & pipes, and all other hard surfaces of equipment. However, wetting porous surfaces with bleach doesn’t work. Minimize porous surfaces in your grow rooms.

Between grows, thoroughly sanitize all surfaces with a commercial-duty hard surface disinfectant. Always pre-clean before using any disinfectant. Let the cleaners clean and the disinfectants disinfect. Here are a few potential disinfectants:

Sanitize rooms thoroughly between grows.

1. Bleach is an effective product. It is easily available and inexpensive. It does have downsides though. Bleach has an irritating odor, it can produce noxious chlorine gas, and is inactivated by relatively small amounts organic matter.
2. Quaternary ammonium compounds (Quats) have been used for many decades as high performance sanitizers. They work by disrupting the cell walls of bacteria. Quats are known to also apply a heavy selection pressure on fungi. A couple of representatives are:
   1. Naccosan, it sanitizes hard surfaces and inhibits the growth of mold and mildew.
   2. Physan-20 is similar to Naccosan but also has a bit of ethanol (should you feel ethanol ever helps).

Monitor and inspect for plant infections on a regular basis, ideally daily. When a new infection is noticed, infected plant parts should be removed when possible. Place them directly into a plastic bag without waving them around. This is your warning alarm to adjust your treatment regimen quickly. More on this in the Treatment section.

Be sure to change your air filters between grows. Bag the filters as you pull them out and remove them from the premises in a closed trash container. Don’t go walking around with a used filter full of … yeuch.

Fungicides are most often grouped by “mode of action” (MOA). They are split into approximately 42 groups that are assigned by the Fungicide Resistance Action Committee (FRAC) based on their modes of action. The two mode-of-action groups most commonly mentioned are Group 3, the demethylation inhibitors (DMI), and Group 11, the quinone outside inhibitors (QoI). Fungicides kill by damaging fungal cell membranes, inactivating critical enzymes or proteins, and/or interfering with key metabolic processes like fungal respiration:

1. Demethylation inhibitors or DMIs (AKA sterol biosynthesis inhibitors) must be inside plant tissue to be absorbed by the fungus. They are a systemic pesticide. This group inhibits sterol biosynthesis in the fungal cell membrane, DMIs do not prevent spore germination or germ tube growth. Triazoles are in this group. Some examples include Banner MAXX, Eagle, Hoist, Rubigan, and Terraguard.
2. Quinone outside inhibitors or QoIs act on a broad spectrum of fungi. They inhibit respiration and impede spore germination. They are excellent preventative treatments. They should be applied prior to infection or in the very early stages of disease development. One type of QoI is kresoxim-methyl products (such as Compass O, Cygnus, and Heritage). Another is the strobilurins such as Quadris® (azoxystrobin). Due to the narrow targeting action of strobilurins, fungal resistance is a major concern.

The best method to prevent or reduce a fungal infection is a multi-pronged approach where you rotate through a few various systemic and contact fungicides. The idea is to use methods that possess different modes of action. Your combinations should aim to provide kill on contact, suppress spore production, and limit the development of resistance. We’ll discuss resistance more later, but suffice it to say that you do not want your own personal superfungus.

Note: When applying fungicides, remember to always test for phytotoxicity (toxic to plant growth) on a small area of the plant before use. Some amount of damage may be deemed tolerable when weighed against the alternative of powdery mildew.

Fungicides designed to attack one single protein or enzyme molecule are said to be “single site acting”. Some examples of this are the triazoles (Group 3), which focus on the demethylase enzyme; the strobilurins (Group 11), which target the succinate dehydrogenase enzyme; and the carboxamides (Group 7) that go after the ubiquinol oxidase enzyme.

Fungicides that attack a wide spectrum of pathogens are referred to as “multi-site acting”. Multi-site fungicides are often used with single site products to reduce the risk of developing treatment resistant fungal strains. Examples are copper (sulfates, oxides, hydroxides, and copper linked to organic molecules) and chlorothalonil (Bravo, Echo, and Daconil). Chlorothalonil targets one fungal molecule, but that molecule is widely used. Copper ions damage enzymes critical for fungal cell function.

Another way to describe a fungicide’s mode of action is to say it is used as a protectant, as a curative, or as an eradicant:

1. Protectants are applied to healthy plants, they employ contact action to prevent fungal spores from germinating or penetrating host tissue. It follows from that that they must be applied before fungal spores infect the plant. Protectants generally are not effective once the fungus grows into plant tissues, so plant tissue that develops after application may not be protected.
2. Curatives are systemic fungicides that generally act within the plant and are effective against fungi shortly after fungal germination. These products must be applied within a certain time after infection starts.
3. Eradicants kill fungi on contact. Recent formulations such as triadimefon and myclobutanil not only kill growing mold but also prevent spore production.

Resistance management is a critical consideration during treatment decision-making. There are two types of resistance: qualitative and quantitative resistance. Qualitative describes an either/or situation: Either the fungus is resistant, or it is not. Either it has, or does not have, the quality known as resistance to the treatment. Quantitative, on the other hand, brings percentage into the picture: Some percentage of the fungi may be resistant to treatment. Some quantity of the fungi is resistant.

For instance, DMI fungicide resistance is almost never 100%. Because DMI resistance is due to more than one mutation, the various organisms will have different levels of resistance. The knee-jerk response of increasing application rate after one pass has failed will usually work in the case of DMI fungicides. Other fungicide groups, like the strobilurins, show qualitative resistance where any application rate becomes ineffective once resistance has developed.

You may have also heard the term “cross-resistance”. Cross resistance exists when a fungus shows resistance to a fungicide because it has resistance to a similar fungicide with the same or similar-enough mode of action.

If you’ve had recent PM outbreaks, it’s not a bad idea to use fungicides protectively before powdery mildew becomes a problem again. Always apply fungicides at their labeled rates and use as many fungicide modes-of-action as possible in your management program.

Resources:

Want to get in touch with Quest Hydro? They can be reached via the following methods:

1. Website: https://questhydro.com/
2. Email: info@questhydro.com
3. Phone: 877-420-1330

When you grow more than a few plants indoors, you may notice that they give off distinctive aromas. Some of the smells come from the soil, other smells from the nutrients, and the plants themselves give off some scents. The scent may be distinct enough that a Gladys Kravitz-type may turn their nose towards your personal interests.

Hey whatcha doin… oh my.

This becomes particularly important now that growing cannabis is increasingly legal in a number of locations. Even if the day comes that all states approve growing cannabis, some strains and varieties release quite a few volatile organic compounds and terpenes in the flowering stage. Good grow lights, such as those provided by Black Dog LED, can increase the presence of these compounds, which may mean the odor may also increase. That might just bug you or your neighbors

If you'd rather keep your horticultural evidence below the radar, here are a few ideas for both casual and serious growers:

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Odor Neutralizers

Most basic household odor neutralizers aren't particularly effective. While sprays, plug-in air fresheners, and other household products can knock down the aroma of a plant or two, they don't last long and aren’t that effective on stronger-smelling varieties. Home air purifiers like ionizers can handle mild household odors, but can't stand up to the fragrance of most aromatic plants.

Not gonna cut it.

ONA Gel is a specially blended product that is popular with many growers because it's easy to use and lasts for 4-6 weeks. Be warned though, don't use these products in the same room as your plants because they can be absorbed by the plants, which will change the taste of the harvest. Confine the use of ONA Gel to adjoining rooms only.

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Commercial Air Cleaners

Experienced growers use filtration units with activated carbon to scrub the air of unwanted odors. They're what you need if you want to really neutralize the scent, and are the only choice for odor control in larger setups with grow tents or dedicated grow rooms.

Since these environments need temperature control and air circulation equipment anyway, adding a filtration system into the environmental controls is a relatively simple proposition. Find the duct size and CFM rating of your ventilation system and choose a filter that will fit and work properly with your system's flow rate. Mount the unit where it's easy to access when it's time to change filters.

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Choose a Plant Naturally Low in Odor

Different strains give off different smells, so give yourself a head start on grow room odor control by picking a variety that's less fragrant but still flavorful and potent. Here are a few to consider:

1. Blue Mystic — A hybrid strain created by crossing Northern Lights and Blueberry for exceptionally low odor.
2. Durban Poison — The South African sativa is nearly odor-free yet has very high THC levels.
3. Northern Lights — A low-aroma variety developed specifically for indoor growing, it's both flavorful and potent.
4. Polar Express — An ideal indoor variety, Polar Express has been crossbred to be compact, flavorful, and extremely low-odor.
5. Sharksbreath — Easy to grow and high yielding, this Indica-dominant variety is very low in aromatics when flowering.

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What NOT to Do

Your plants need fresh, well-circulated air to thrive. Stagnant, poorly conditioned air is a surefire recipe for disaster, so don't seal off your growing area in order to contain odors. If you're able to vent to the outside of your building with a filter, that's your best choice for odor control. Just be sure to locate your vents where they won't intrude on unwelcoming nostrils.

Resources:

Want to get in touch with Black Dog LED? They can be reached via the following methods:

1. Website: https://www.blackdogled.com/
2. Email: sales@blackdogled.com
3. Phone: (800) 380-2291