What are those rusty looking spots on your leaves? What bug is eating your buds? Why are your sativa sprouts covered in fuzz? This book contains all-organic solutions plus best growing practices to avoid problems before they start.
The Daily Marijuana Observer had the pleasure of sitting down with David and Kathryn to learn more about how the two got into plant pathology, and more.
What got you into plant pathology?
David: My first wife died of cancer, of Hodgkin's Disease, many years ago when it was still incurable. Shortly after her death her cancer became curable thanks to a plant, the Madagascar periwinkle, Catharanthus roseus. I became extremely interested in botanical medicine as a result.
Some of my earliest memories are of gardening with my father; I followed in his footsteps and have been gardening all my life. As a child my fascination with bugs in the garden got me started on the path to pathology. In college I majored in Botany as an undergrad. In graduate school I got a PhD in Botany, and eventually became an assistant professor of Plant Pathology at the University of Hawaii.
Kathryn and I have owned and operated commercial nurseries where the efficient and effective management of pests and diseases is critical. My passion for protecting consumers, growers, and the environment led me to organic remedies.
Kathryn: My long standing interests in ecology, conservation biology, and eco-tourism led me to an interest in understanding the processes of the natural world in the garden. This interest led me to promulgate the use organic practices in the garden.
We notice you have four other gardening books, are they all focused on all-organic solutions? How is growing marijuana organically important?
Yes, we have four other books in our "What's Wrong With My Plant..." series, all of them exclusively recommend organic solutions for plant problems. It's important to avoid synthetic pesticides for the user, the grower, and the environment; particularly on any plant you are going to eat. Marijuana is ultimately going to be ingested, inhaled, or absorbed into your body when you use it, whether it's for medical or recreational purposes. If the marijuana has residues of synthetic pesticides on it, those pesticides can be transferred into your body in the smoke, or the edibles, or the concentrate. The unfortunate consequence is that pesticide poisoning can be serious, especially for medical patients whose health is already compromised.
Do you grow yourself and what do you find is the most common problem that people run into when growing marijuana?
I first grew cannabis outdoors in 1971 and indoors, under lights, in 1973. At the moment we do not grow cannabis because our book is popular and might attract attention that would make us vulnerable under federal law.
The most common problems people run into are poor growing conditions; pathologists call these abiotic disorders. These conditions include: too little light; temperatures that are too hot or too cold;, insufficient water or too much water; nutrient deficiencies, and/or poor soil. Plant pathologists generally use a rule of thumb, known as the 80/20 rule: 80% of the time plant problems are due to abiotic disorders. On the other hand, the most common pests of marijuana are spider mites, hemp russet mites, and broad mites. And finally, the most common diseases are gray mold and powdery mildew.
Who do you feel would be the ideal reader for this book?
Both home and commercial growers will benefit from this book. Whether the cannabis is grown for medical, spiritual, emotional, or recreational use all growers need a quick and easy way to diagnose any problem that arises. We organized all the problems by plant organ (leaf, stem, flower, root, etc.), with a good photograph of symptoms that can easily be seen with the naked eye. Beside the photo is a written description of the symptoms so you can match the photo and the description to the symptoms you actually see on your plants. When you find a match then you have a diagnosis. Once you have an accurate diagnosis, there's a reference to the organic solutions in the book. You always start first by changing the growing conditions, second you apply biological controls, and third you use organic remedies.
We've observed numerous instances in online marijuana forums where a grower has a problem, posts a photo, and asks for help. Many of the responses from other growers are misleading at best and totally wrong at worst. There is an enormous amount of misinformation on the web that is a disservice to this burgeoning industry. Our book is well researched and accurate. It gives growers the tools they need to be successful in their enterprise.
What type of Marijuana plant do you find is the easiest to grow and why? Also, where do you think the best places to grow indica and sativa are in the world?
All marijuana is pretty easy to grow (there's a good reason why it's called a weed). That doesn't mean cannabis plants won't get into trouble; they can and will.
The easiest cannabis to grow are feral ruderalis hemp types. Ruderalis strains are day-length neutral (i.e. auto-flowering); short in stature (1.5 to 2 feet tall); and somewhat resistant to molds. They are generally low in THC and high in CBD; and are a valuable genetic resource for medicinal strains of cannabis.
Sativa dominant strains originated in the humid tropics and are also somewhat mold resistant. They are very large plants sometimes growing 15 feet or more tall. They are very high in THC and low in CBD. The size of these plants can be difficult to accommodate in the average garden.
Indica dominant strains originated in the dry climates of central Asia such as Afghanistan and Hindu Kush. These plants are shorter (to 4 or 5 feet) than sativa types and taller than ruderalis types. Indicas can be very high in THC. They are more susceptible to mold infections because they originated in dry climates.
As we visited with growers while writing our book we found modern hybrids (sativa x indica) like Blue Dream, Gorilla Glue, and Dutch Treat were popular and pretty easy. Hybrid strains are generally easier to grow than "pure" sativa or indica strains. We also found Green Crack, a sativa type, to be pretty easy and popular.
Best places to grow indica strains are dry summer climates with low humidity and a long enough growing season that autumn rains aren't going to ruin the crop. In the US, the Pacific Northwest, Southern Oregon, California, and the desert Southwest are all good locations for indica strains. Dry summer climates in other parts of the world (Australia, the Mediterranean, South Africa, Chile) and warm desert climates (Middle east, northern Africa, etc.) are good for indica types.
Best places to grow sativa strains have warm, humid summers with a long growing season. In the USA, that would include Eastern and Southeastern states. Warm, humid tropical climates of the world (Mexico, Thailand, Brazil, Argentina, China, etc.) are good for sativa types.
What would be your best advice for a first time cannabis grower?
Research the strains online thoroughly to find ones that suit your purposes. In addition research your state's laws to be certain of your legal status. Do all of this research before you purchase any seeds or clones. Talk to other growers in your area because your climate and soils have a huge influence on the terroir (aroma and flavor) of your crop's suite of terpenes (aromatic oils) and on the entourage effect (combination of active ingredients) of your crop. And finally, be prepared with a sensible organic approach to fix any problems that arise.
Where do you see the marijuana industry going in the next five years from a grower's aspect?
Ideally in the next five years we will see Cannabis taken off the Schedule 1 Controlled Substances Act. Furthermore it should become legal nationwide for both medical and recreational use. Anyone who wants to should be able to grow their own.
Commercial growers will pay very close attention to their crops and to organic production methods over the next five years. There are still some growers today who use synthetic pesticides, perhaps because it's easy and convenient and they don't know any better. But the financial risk of having your whole crop condemned and all your product pulled off the shelves because pesticides have been detected by the labs is just too great.
We're going to see continued improvements in strains from expert breeders. We'll no doubt see higher THC content for the recreational market. Medical strains with high CBD content will address an increasing number of conditions. We'll also see stabilized feminized seeds and auto-flowering develop in more strains.