What Are These White Spots?

Question: What are the white spots on my trailing ivy?

Answer: Well, they could be lots of things… A really great thing to do would be to invest in a magnifying glass (I use the word “invest” here loosely, since magnifying glasses can be bought most anywhere and are pretty cheap). It is underestimated how helpful they are to gardeners. These white spots you speak of could be aphids, which can be a gray color. They also could be spots where hard water has landed on your plant and evaporated, leaving salts and metals behind. A picture would be awesome, so I could identify it for certain, but let’s entertain my first notion: Powdery Mildew.

This is powdery mildew on squash leaves just like I had this Summer. It nearly cost me my squash harvest, until someone gave me a great tip...

I had powdery mildew (PM) outside in my backyard earlier this Summer. It appeared on the large leaves of my squash plants. These leaves were robust and had thick stems. When mature, the leaves measured a foot across or more! The mildew worked its way across the leaves, forming islands of PM in my squash patch. The leaves would turn speckled and white. Then they would yellow, wither and die.

A good friend of mine noticed this process happening and suggested a remedy that he had learned from a friend of his (as often is the case within gardening circles).

MILK!

Take one part regular cow’s milk (soy milk and other milk substitutes will not work) and dilute it with four parts water. Put this mixture in a spray bottle and spray it on the leaves of your plant. The lactic acid in the milk will kill off the powdery mildew and keep it from ravaging your plant. This past Summer, I had to spray about once a month to keep new leaves from being infected as they grew. You may not have to repeat the process as much as I did, since your ivy plant is (I assume) not growing at the same rate as a cultivated vegetable garden.

Now, since you are indoors, you should be careful about dripping and splashing. Sour milk is not a good accessory to indoor gardening! The mixture that actually falls on the leaves will not produce a smell, but you don’t want this stuff pooling under your couch. You may want to put your plant in the sink to spray it down with the milk concoction, allow it to dry, then return it to its home.

Often, I have heard that over watering is the main reason for powdery mildew. Indeed, we think of moist environments as prime areas for mold and mildew to develop. However, PM can come about even in arid environments. Even so, trailing ivy is a plant that does not like to be over watered, so cutting back on your watering regimen couldn’t hurt.