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MMWD Blog: Think Blue Marin

Welcome to our blog! Written by staff at MMWD, “Think Blue Marin” explores all things water in south and central Marin—water supplies, conservation, new projects, watershed management, and more.

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Oct 20

Plant Damage

Posted on October 20, 2017 at 10:44 AM by Ann Vallee

by Charlene Burgi

There are times as a gardener when we find plants struggling and in need of special care. Often that care necessitates further investigation before proceeding with treatment to ensure the problem is corrected.

Lilac leaf damage
 Lilac leaf damage
This past week more than one issue arose among my own plants. My walk through the garden brought a flurry of hopping insects. It didn't take long for the leaves on the redbud tree and lilacs to tell the story of grasshoppers supping very well, as those pretty, heart-shaped leaves took on a new, scalloped appearance. An easy fix was to dust the plants with flour to curtail the dining. My research further pointed me to a recipe using neem oil and crushed garlic. Spraying a white vinegar solution onto the annual weeds also could eliminate a bevy of problems—while creating a desire for tossed green salad for dinner. And speaking of dinner, it seems the sudden appearance of many praying mantises assisted with the grasshopper eradication. They had found the feasting table right in the backyard!

The damage assessment didn't end with grasshoppers. As I glanced out the kitchen window, I saw that the hybrid tea rose ‘Love’ looked extremely wilted. Notably the evening temperatures here in Lassen have dipped into the 20-degree range, so I wondered if the problem was frost damage. Upon further investigation, I noticed that another rose planted 12 feet way seemed untouched by the cold, which ruled out weather as a factor. It was time to grab a microscope to dig deeper as I checked for insect damage. However, the dying plant was clean. I then wiggled the plant to see if the roots were secure and not destroyed by gophers. The rose sported some very healthy thorns so admittedly my wiggling attempts were a bit feeble. Still, given what little I could find, I determined that the roots initiated the problem. In response, I opted to prune back the rose to a foot off the ground. My thought was to see if any new growth would be generated by cutting back the plant. Surely without a four-foot plant for the ailing roots to support, there may be some hope for survival. 

The decision to prune back this hard before winter was a concern. Coincidentally, a friend living in heavy snow country contacted me to ask how to protect roses during winter. The advice I shared was not to prune now and instead bank up mulch around each rose to protect from heavy snowfall. My own once-beautiful rosebush looked like it suffered from a very bad haircut, and on top of that it still needed protection from the winter cold. As I looked about the garden, the 17 peonies lay prostrate on the ground, begging to be pruned back. The a-ha moment of using their foliage to act as a rose blanket seemed a good solution. Hopefully these measures will support new growth for the rose, but all I can do now is wait until spring to find out.

As gardeners, we have to confront and address various types of damage whether it be insect, frost, mechanical or disease. The most important factor in dealing with the damage is to determine the cause, take necessary steps to address the issue, and remove any dying or diseased portion of the plant. Just remember any diseased plant material should not be added to a compost pile. If you’re not able to identify the problem, contact Marin Master Gardeners or the local Farm Advisor to discover what you are dealing with and follow the instructions prescribed for a healthy solution for your garden.


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