By: Liz Baessler
Paclobutrazol is a fungicide that is often used not to kill fungi, but to slow down top growth on plants. Keep reading to learn more about paclobutrazol effects and uses.
What is paclobutrazol? Technically, paclobutrazol is a synthetic fungicide. While it can be applied to kill fungi, it is much more commonly used as a plant growth regulator. Plant growth regulators are used to slow down the top growth of plants, encouraging root growth and thicker, stouter existent growth.
This is especially useful in lawns, as it makes the turf thicker and reduces the need for mowing.
Paclobutrazol works as a plant growth regulator in two ways. First, it inhibits the plant’s ability to produce gibberellic acid, which reduces the plant’s cell length. This makes the plant gain height more slowly.
Second, it decreases the destruction of abscisic acid, which makes the plant grow more slowly and lose less water. Basically, it makes the plant stay shorter and stouter for longer.
Paclobutrazol effects are not limited to growth regulation. It is, after all, a fungicide, and it can be used as one. Some research has shown that it can actually be used to kill bacteria. It has also been shown to promote richer, greener growth, and to increase a plant’s ability to take in nutrients and minerals.
It can be used in lawns to suppress the growth of unwanted bluegrass.
Paclobutrazol can be absorbed somewhat through the leaves, but it can be taken in much more effectively by a plant’s roots. Because of this, it should be applied as a soil drench. It is also included in some fertilizer mixes.
To use paclobutrazol to suppress bluegrass, apply it to your lawn in both the spring and autumn.
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Hot July, Dry August
A resounding sigh of relief was felt over much of the state as July passed. It was the second hottest July on record in Minnesota, and the hottest in 118 years of records throughout the rest of the country. Precipitation around the state varied greatly. From record droughts in northwest and parts of southern Minnesota, to record floods in the northeast, this summer was anything but typical. Homeowners in the Twin Cities metro should feel very fortunate to not be dealing with the after-effects in these areas. Still, if you were able to sustain the quality of your lawn throughout July, it was truly a blessing.
August came and went fairly quickly with very little love from Mother Nature, almost a three inch rainfall deficit in the Twin Cities. Again, parts of southern and northwestern Minnesota suffered the worst. The map on the left from the MNDNR State Climatology Office puts precipitation deficits into perspective across the state from June 19 th to September 3 rd . September has started off dry as well, with only trace amounts of rain recorded over the last two days. What implications does this have on your fall lawn care practices? I’m glad you asked.
Fall is the preferred time for many important lawn care practices. From fertilization and weed control, to cultivation and seeding, there is absolutely no better time for cool-season turfgrass maintenance in the Midwest. But this year is different. The lack of precipitation in August has caused many of our Kentucky bluegrass, perennial ryegrass, or fine fescue lawns to brown out and cease growing, almost a revert back to summer dormancy for those homeowners that lack the availability of adequate irrigation. In order for your lawn to recover, you will need to begin irrigating regularly. This means more than just one or two cycles, but enough water to wet the root zone sufficiently to sustain turfgrass health.
Avoid placing additional stress on drought-stressed lawns
Speaking of turfgrass health, if your lawn is stressed from lack of moisture, typical fall maintenance practices that we’ve recommended in the past will add additional stress. In this case, we might actually see our lawn quality decline from the practice, for example: aerating.
The best advice that I can give you is to determine the growing conditions that are furthest from optimum and correct those first. If your lawn is declining from a lack of moisture, irrigate. If you’ve been irrigating with little turfgrass response, soil compaction may be an issue, in which case aerating would help. Has your fertility program been adequate? Are there insect or weed pressures? These are all questions to consider.
Concentrate more this fall on creating the best possible growing environment for your turfgrass, and you will reap the benefits during next year’s growing season. Adding turfgrass stress to an already stressful situation will do more harm than good.
Tips for drought-stressed lawns
Return adequate soil moisture levels and turfgrass health before you conduct these practices.
BELFAIR, Wash. -- Other than a skunky aroma, the waiting room at the Cannabis Care Foundation in Belfair, Wash., resembles your typical pharmacy. Chairs line walls next to stacks of magazines -- in this case, issues of Rolling Stone -- and a steady stream of patients step up to the counter with doctor's notes.
One by one, salesman Adam Dempsey leads them to the back of the shop, where they can choose from an extensive weed menu -- products with names such as Frankenstein, Garbage, Snoops Dream and Sour Diesel.
"I take it every day myself," said Dempsey, sporting a black hat with a green embroidered marijuana leaf and a plain white T-shirt over his tattooed arms. He works security and customer service at the non-profit store, which through a cooperative arrangement gets much of its cannabis crop from patients themselves.
Marijuana's primary mind-bending ingredient, tetrahydrocannabinol (THC), Dempsey suggested, helps tame his attention deficit disorder.
But experts warn that unwelcome chemicals, including pesticides, may be tagging along with the THC and threatening the health of marijuana users.
"There's a pretty considerable amount of contaminated cannabis," said Jeff Raber of The Werc Shop, a Pasadena, Calif.-based lab that tests products primarily for California dispensaries.
"There are no application standards," he added. "Since we're not telling growers that they're allowed to use anything, they often use whatever they can get their hands on. And that's a lot of bad things."
Many of the chemicals applied to pot plants are intended only for lawns and other non-edibles. Medical cannabis samples collected in Los Angeles have been found to contain pesticide residues at levels 1600 times the legal digestible amount.
Because the product is generally inhaled rather than eaten, any toxins it carries have an even more direct route into the lungs and blood stream. Raber noted the situation is all the more concerning for patients smoking medical cannabis, whose health problems could make them more vulnerable to the risks pesticide exposure brings -- especially if they suffer from a liver disease.
Still illegal in the eyes of the federal government, marijuana use is condoned by a growing number of states. Eighteen states and the District of Columbia now allow the medical use of cannabis, and Colorado and Washington recently approved pot for recreational use. Many of the states where some form of marijuana use is legal, including Washington, have begun drafting regulations that would require independent labs to test products before they are sold.
While efforts to legalize both medical and recreational cannabis could lead to "a greater awareness of and demand for clean, pesticide-free marijuana," said Raber, the burgeoning market remains troublesome.
Raber published a study this month that attempted to answer some lingering questions about pot and pesticide exposure. He and his colleagues investigated pesticides they'd commonly detected on marijuana products in their lab -- bifenthrin, diazinon, and permethrin -- as well as a plant growth regulator called paclobutrazol. One concern was whether those pesticides could actually get into a user's body.
The short answer: yes. However, amounts varied depending on how the pot was smoked.
The researchers determined that as much as 60.3 percent to 69.5 percent of chemical residues would be inhaled with a hand-held glass pipe, but as little as 0.08 percent to 10.9 percent got through with a filtered water pipe.
"When you filter, you see a dramatic reduction in the amount of pesticides," said Raber.
Not all cannabis is the same, of course. Each strain comes with its own unique combination of chemical compounds, and scientists have yet to get a handle on how any of the chemicals applied to the plant might interact with those natural chemicals, especially when burned and inhaled together. Then there are all of the other forms in which cannabis is consumed -- from oils to teas to candies.
"This raises a lot of questions on how to set up better structures to provide clean, regulated supplies," Raber said.
Public health experts interviewed by The Huffington Post lamented the dearth of data on the subject. Some research has been done on pesticides and smoking tobacco, but since tobacco is not a food crop, the U.S. Environmental Protection Agency has not set tolerances on pesticide residue levels.
Tobacco is also generally smoked through filtered cigarettes, and for the most part not targeted for use by already unhealthy adults, as medical marijuana is.
"If the pesticide is inhaled, then this is quite worrisome," said Dr. Beate Ritz, an environmental health epidemiologist at the University of California, Los Angeles School of Pubic Health. "And these patients might be much more vulnerable."
"Pesticides affect the nervous systems of insects. Our nervous systems are similar to theirs," added Ritz, noting that for patients with terminal illnesses, the benefits of smoking marijuana might outweigh long-term risks of pesticide exposure, such as cancer and heart disease. But acute risks such as flu-like illnesses and respiratory problems, she said, would still be a serious concern.
Given all this, it seems reasonable to ask whether pesticides are even necessary to grow marijuana plants. The answer depends on whom you ask.
James Dill, a pest management specialist with the University of Maine's Cooperative Extension, explained that pests create difficulties in managing the crop. Too much moisture and growers face a fungus or mildew problem too much dryness and spider mites can take over.
"All of the sudden you could be smoking a mold," said Dill. "That's not meant to be ingested."
It can be easy to see why growers motivated to fend off these foes, and by constraints on time and space to grow plants faster and taller, might resort to chemical help.
There are some alternatives.
"If they're smart, they use companion planting like garlic and onion chives to provide a natural barrier," said Dempsey, the Washington marijuana dispensary salesman.
Still, he admitted that his suppliers, many of whom are also his customers, are still just "learning how to grow."
The Cannabis Care Foundation doesn't have any special testing equipment, nor does it send marijuana out to a lab for analysis. But Dempsey suggested that he and his coworkers can "tell pesticides right away" by smell, taste, touch or by using a microscope. He added that they reject a good amount of cannabis due to mold, pests or pesticide contamination.
But Raber expressed doubt that such surface-level analysis would be sufficient.
"There is no way they could detect pesticide molecules inside of the plant that were put there through the roots," he said. "Nor could they smell the tens to hundreds of compounds you'd like to look for that could potentially be put on there by a cultivator."
Pesticides can be dangerous even at levels far lower than someone would be able to see with a microscope, he added. But he also emphasized that most dispensaries and cultivators want to provide a clean, safe product. In many cases, both seller and grower are unaware that a crop has become contaminated.
"Cannabis is well known to pull up a lot of crap out of the ground," he said.
Evan Mascagni stumbled across the issue of contaminated cannabis while filming his upcoming documentary, "Toxic Profits," which highlights the global sale of pesticides banned in the U.S. He noted concern among many in California that because marijuana remains illegal under federal law, the U.S. Department of Agriculture doesn't allow any organic certification for its products.
Some independent efforts such as Clean Green Certified have sprouted, but even crops from growers who think they are complying with organic standards sometimes test positive for pesticides.
"You can only imagine the pesticides that are being used on marijuana grown elsewhere by profit-driven farmers" who may not care about the health of consumers or the environment, Mascagni told HuffPost in an email.
Pot-smokers aren't the only ones at risk from the application of pesticides on marijuana crops. Also potentially in danger are the people spraying the chemicals -- especially if the practice takes place indoors -- and others that may eat, drink or breathe downwind.
Dempsey maintained that growers can produce cannabis without using pesticides.
"This is a pharmacy," he said. "We need something that helps a patient get healthier, not something that kills them."
There’s some really good information here for all of you homeowners looking to avoid the leaf raking process this weekend. The real answer to this question is NO, but it comes with one catch……he most important point with fall cleanup is that the tree leaves are not covering a significant portion of the turfgrass canopy. 10-20% coverage of your lawn might be okay, but I certainly would make sure the leaves aren’t covering any more than that. Excessive leaf matter on your lawn going into winter is bad for several reasons. First, it will smother the grass and if not removed very soon in the spring it will inhibit growth. Second, it can promote the snow mold diseases. And finally, turf damage from critters (voles, mice) can be more extensive in the spring.
The homeowner basically has three options to make sure that leaves are not covering a significant portion of their lawn:
1) Rake them up or use a blower- compost the leaves or dispose of them
2) Use the bagging attachment for your mower: compost the leaf/grass mix or dispose of
3) Mulch the leaves with a mower (i.e. chop them into small pieces so they will fall into the canopy). This is my preferred option because the nutrients and organic matter will benefit the lawn and soil. Some leaf types have been shown to reduce weed seed germination when mulched into a lawn canopy (maples, others). The leaves of some particular tree species (legumes like honey locust, others) might actually add a significant amount of nitrogen to lawns because these species fix nitrogen from the atmosphere just like soybeans, so higher leaf nitrogen contents in these leaves is possible. Additional resources for these two concepts are here:
Successfully mulching leaves into a lawn canopy requires more frequent mowing in the fall and possibly several passes with the mower to mulch the leaves sufficiently. Specialized mulching mowers can also be purchased, and these mower types will also be beneficial year-round to mulch grass leaves into the canopy. Chopping leaves into small pieces is important.
As always, please let me know if you have any questions on this information: [email protected]
Tree leaves that have built up to this level in your lawn would not be practical to mulch into the lawn canopy. Removal would be required in this situation. Photo: Sam Bauer
Moderate levels of tree leaves can easily be mulched into a lawn canopy, such as the situation shown here. Photo: Sam Bauer