Powdery mildew and other pesky plant problems

Linn County Master Gardener, Claire Smith, offers the following advice on the care of houseplants:

Oh, the joy of a fall day in Iowa.  Yesterday I donned my down coat for morning chores.  By afternoon, it was t-shirt time.  Today I was outside in a sweatshirt.  Anticipating the wet weather forecast, I've been hustling around with last minute fall busyness of emptying, cleaning and storing outdoor flower pots.  Discarded soil amends an existing bed and it's recommended we use fresh potting soil each spring.  Soaking the pots in a mild bleach solution, then thoroughly rinsing and stacking in our shed eliminates potential problems next spring.  Then there's one final lawn mowing experience on the agenda before the mower gets a good bath and general going over.

Because preventative measures are always a good idea with plants, the indoor plants who resided on the deck all summer got a mild detergent bath, good rinse and dripped dry on the deck before coming inside this week.  Charlie said, “Gramma, it looks like a forest in here”.  I suppose it does when several Mother-in-law Tongues are taller than you and the Spider Plants, Ivy, Hosta, Philodendron and Aloe Vera are spilling over into where you should be putting your sweatshirt and shoes.

If you do discover a pest or disease problem, isolate the afflicted plant(s) until the issue can be resolved.  If you choose to discard the plant, discard the soil and sterilize the container before reuse.

Be certain to thoroughly inspect any new plants you plan to purchase and buy from a reputable garden center or horticultural organization.  Fortunately, most house plant problems are more of a nuisance than a real problem.

White to gray powdery leaf spots are due to a disease called powdery mildew. This disease enjoys humid and cool environments.  Powdery mildew can be rubbed off the plant surface.  Other diseases caused by various fungi and bacteria will blemish foliage.

Houseplants can be attacked by a variety of pests.  While pests generally don't create a lethal situation for plants, they are very annoying.  Leaves may yellow, or become speckled, brown or be covered with webs.  Whiteflies may cause leaves to drop.  Aphids cause stunted and deformed plant growth.

Watering-actually overwatering-is one of the most common indoor plant problems.  Root rot can be triggered by overwatering because waterlogged soil doesn't contain enough air for plants to breathe and they may become too weak to fight off fungi.  Rotted roots can't uptake water and will cause the rest of the plant to wither.  Be care to not drench foliage as fungi and bacteria can spread on damp leaves from splashing water.    My Mom had a real regimen with her plants.  She ALWAYS watered on Wednesday morning.  Some plants got water once each week, others once each month-that was always on the first Wednesday, still others twice each month-on the first and third Wednesdays.   She believed in watering from the bottom up and those saucers had better be clean and free of any residue.  She had Violets that flowered ‘til the cows came home and Philodendron that cascaded from a repurposed lamp base fully four feet to the floor.

Following good general plant care techniques will usually control pests and pathogens. Simply provide the proper attention the plants deserve and they will provide you with the enjoyment you deserve during the long cold Iowa winter.