Letters to Maximum Yield
First I'd like to commend everyone on the great magazine, very informative, and the best thing about it that its pretty much in laymens terms which is a real asset to the beginner. I have a question concerning odour elimination. Currently we have a 10 X 10 room. What would be idea for this application. I think I ran across something in your magazine by the name of an ozone generator combined with the use of some type of ultraviolet light. I appreciate any and all feedback. Thanks, koolkat KoolKat: As the saying goes, there is more than one way to skin a cat. Some popular methods of odour contol that are currently available are: chemical odour eaters/masking agents, ultraviolet ozone generators and corona discharge ozone generators. Your room is likely less than 1000 cubic feet. Chemical agents such as "Ona" or "Odour Killer" may offer temporary odour control, but need to be replenished frequently and are not as efficient as U.V. or C.D. ozone generators for odour control.
Your grow room (due to size) does not require a Corona Discharge generator, as these are best used in larger applications. Ozone can be dangerous, so it is best not to have concentrations that are higher than required. An ultraviolet light, which is similar to a flourescent bulb in apperarance, is likely your best bet. There is more than one way to go about using this for odour control. If you are exhausting to the outdoors, a u.v. light can be installed in your air duct leaving the grow room. The lamp would be on the same circuit as your exhaust fan, so it would come on only when the "undesireable" odours are to leave the building. The lamps require special ballasts, so make sure your local retailer provides you with a complete unit.
The light should be sealed into the ducting, just after the exhaust fan. This light could seriously damage your eyes, skin, lungs, etc., so great care must be taken to ensure that there is no u.v. light leaking from ducting.
If exhausting outdoors is not an option, the grow room exhaust could be vented into an unused room or attic. If this room is tightly sealed, a low wattage u.v. lamp could be placed in the room to eliminate odours. This room would then act as a sort of mixing chamber for odour control. Again, the bulb should be sealed in an enclosure. A small axial fan in the sealed unit is used to carry skunky odours past the lamp in the enclosure, removing unwanted smells, spores, etc. thus "cleaning" the air in the spare room/mixing chamber. These units are commercially available at your local grow store. Do not place such a unit in the grow room, it may damage your plants, reduce flavour and aroma, and injure you while you are tending your plants. Erik B
I enjoy your bi-monthly magazine. I was wondering if you could help me to find a good long term cure for mould on the leaves of my plants. Anything I should be doing? I would appreciate any information you have and look forward to your magazine. Thank you, Mike. Vancouver
Prevention is the best long term cure-bar none. If you have had a mold problem in the past, you must sterilize your growing area and equipment. Before you introduce your next crop to the growing environment.Scrub down the walls and systems with a mild bleach solution. One part of bleach to ten parts water is adequate. Rinse/scrub with lots of fresh water. Irrigation lines can be flushed with a hydrogen peroxide solution.
High humidity in the growing environment is usually attributed to foiliar fungus problems. Make sure your humidity is less than 60% during dark cycles humidity is usually the highest. Wire a dehumidistat to your vent fan or dehumidifier. Ensure that the plants are not touching walls or each other, especially floral clusters. Good air circulation in the plant canopy is essential, so have an oscillating fan gently blowing on your plants 24hrs a day. Increased potassium levels have been shown to increase plant resistance to mold problems. If growing in soil, let the top 1/2"-1" of the growing mix dry out before watering, as this is a breeding ground for mold/fungal spores. Just stick your finger into the soil to determine when to irrigate.
Most plants grown today have been hybridized. Try growing a variety with more of a tropical lineage. Plants that have originated in dry, arid conditions, such as Afghanistan, are more likely to have mold problems when in a humid environment. Tropical varieties generally take longer to mature, but the results can outweigh the additional time spent in flowering.
If you are in mid crop, try using garden sulpher in a foiliar spray. It is available in a ready made spray by Safer's called "Defender." Always follow the manufacturer's directions carefully. Good luck.
Hi: I have a question for you about using Oxy-Cal. I noticed a slight yellowing between the veins on the leaves which appears to be caused by a Magnesium deficiency. According to Maximum Yield's latest issue on p.26, this could be caused by excess Calcium. I used Oxy Cal on the sunshine mix. Is it possible that I applied too much? I use General Hydroponics and follow their feeding program accurately. If I did use too much Oxy Cal, how can I reduce its affects and raise the Magnesium levels?? Thank You for time, Matt
Some rather expensive studies by the Canadian Federal Government have been conducted on tomato plants with regard to the ideal calcium: magnesium ratio.
In hydroponic systems, 150ppm Ca : 50ppm Mg have been shown to result in greatest yields in control groups (all other factors being equal). Towards harvest in peat soils, the pH of the medium has usually become excessively low due to copious quantities of commercial fertilizer building up over a period of time. Magnesium becomes less available to the plant with decreasing pH. It is worthwhile to note that magnesium may not be the problem, but my response is assuming your diagnosis of magnesium deficiency is correct.
Studies suggest that excess potassium at the root zone is often suspect to locking out magnesium, which is the largest component of chlorophyll in higher plants. Reducing levels of potassium in the last few weeks before harvest, and maintaining a pH of 6-6.3 may help to alleviate this disorder.
Magnesium deficiency may not reduce overall yields, especially when the plant is putting it's final efforts into filling out blooms, as it is required most when leaves are rapidly developing. However, it may become a gateway for pathogens to enter the plant, thus, reducing yields. Some commercial vegetable growers are able to supply the majority of the crops magnesium requirements via frequent foiliar sprays. Magnesium is also available in a chelated form (more available to the plant). Dolomitic lime can help to maintain a stable pH, and contains magnesium. One cup of dolomitic lime per cubic foot of Sunshine Mix can work wonders for many varieties.
I hope that this helps, and always follow the manufacturer/packager's directions carefully.