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Gardening Tips: Plants that burn

July 5, 2019 11:47 am Updated: July 5, 2019 11:48 am


The recent summer like weather and ample rainfall has really accelerated the growth of our gardens, as well as the weeds that compete with them. Last year at this time I was complaining about the serious drought we had experienced for the previous summers of 2016, 2017, as well as early in the summer of 2018. Well, that all changed sometime last August when the rains began and the overly wet trend has continued right up until now. We are still experiencing showers at least two or three times a week, but some parts of the region are actually in need of some rain right now due to the evaporative transpiration that occurs every summer at this time.

I have been using my overly full rain barrels to water my window boxes and potted plants of course. I made a blunder a few weeks ago when I decided to use an alternative method of mosquito control in the barrels. Normally, I use “mosquito dunks” to control the mosquito larvae and this product is very effective, as well as harmless to most other living organisms. This year I ran out of the “dunks” a couple of weeks ago, so I decided to add some canola oil to the barrels instead. Mosquito larvae need to breathe air even though they are aquatic, so putting a floating film of oil on the surface of the water will effectively suffocate them. I have a lot of canola oil on hand, since I use it in my chainsaws in place of bar oil. It is far less expensive. I am not recommending this practice because chainsaw manufacturers recommend using only approved “bar oil,” but my chainsaws are old and they seem to run just fine. One downside is that the saws smell like I am cooking French fries when they are running. Bears may also decide to chew on the saws if they are left outdoors, due to the tasty aroma they emit. Anyway, the canola oil seems to have acted as a nucleus or magnet for all sort of organic matter to congeal around it in the barrels and the result has been rather disgusting. I am reluctant to even use this water at all now, since it is so slimy. It also seems to have attracted some rodents and so far two chipmunks and a mouse have drowned in one of the barrels! I will dump the barrels before the next T-storms and add mosquito dunks when they refill.

In our region there are very few plants that we need to avoid contact with, but there are three or four that can cause serious rashes if we get their sap on our skin. Poison ivy is the most common and everyone who ventures or gardens outdoors should learn to recognize this nasty native. “Leaves of three, let it be” is a good adage to adopt when working or playing outside. Poison ivy always has 3, shiny green, compound leaflets on plants that may grow as a trailing vine beneath other vegetation or as a shrub-like plant, or a climbing vine with a very hairy stem that clings to tree trunks. The leaf shape is highly variable, ranging from slightly lobed, almost oak shaped to egg shaped.

The other three rash causing plants are closely related, being in the parsnip family. Giant hogweed is hard not to recognize by its giant stature. It is a huge plant, growing 10 to 20 feet tall in full sun, with large, white, compound blossoms, up to 2 feet wide that might tempt some people to pick and take home. That would be a very bad idea! It is not native, but it is spreading across much of New York, mostly along roadsides. The hollow stems are 2 to 4 inches thick, featuring reddish, or purple blotches and the compound, highly dissected leaves, which clasp the stem, may be up to five feet long. It resembles Queen Anne’s lace, or wild parsnip and cow parsnip, which are the two other common native plants that also have poisonous sap.

Of these three, the most common is wild parsnip, which may also grow 6 to 8 feet tall, but has bright yellow flowers and is just now beginning to bloom in our region. It is very common along roadsides and seeds itself readily in backyards. I would urge gardeners to be very careful while using weed whackers since these tools can splatter the highly infectious sap everywhere! Pictures of all of these plants may be found here

Since all these plants are attractive and widespread, perhaps the best strategy is to learn to avoid them rather than attempting to eradicate them.

Reach Bob Beyfuss at