Anyone growing tomatoes or potatoes needs to be on the lookout for signs of late blight. By mid-July this devastating disease had been found on potatoes in western New York and western Vermont.

This means Northern New York is basically surrounded by it and the cool, wet weather we had in June through mid-July created ideal conditions for this disease. Only tomatoes and potatoes are affected by this particular pathogen.

Take Steps to Prevent Spread

Late blight is devastating because it kills tomatoes and potatoes within days of infestation and also because it spreads so easily and quickly from garden to garden. Home gardeners with just a couple of tomatoes may be tempted to abandon infected plants, but these plants will serve as a breeding ground and continue to spread spores throughout the neighborhood. This ‘hop-scotch’ ability is what makes late blight such a public problem. It is bad enough that gardeners should lose their crop, but even worse if they allow it to spread to other gardens.

Once late blight is confirmed please bag up infested plants and take them to the landfill. Larger scale plantings can be carefully burned or buried deeply and away from the garden.

There is a lot of confusion about the various diseases tomatoes get, so when in doubt, drop off a few leaves in a sealed plastic bag to any Cornell Cooperative Extension (CCE) office for a free diagnosis. Pictures can be emailed to CCE as well; CCE educators will let you know if an actual sample is needed.

The website http://www.usablight.org/ has lots of information on the occurrence of late blight as well as excellent information on symptoms, look-alike problems, and management options.

Hanging Baskets and Planters

By August, hanging baskets of flowers are nearing exhaustion. They are filled with plants early in the summer to provide instant color but by the hot days of August they are crowded and tired. Some may be ready for the compost pile. Don’t feel bad, you had several weeks of beauty from them. Those 10-inch baskets can only last so long.

Depending on their size and how much room for root growth they have, planters, tubs and window boxes will need some extra attention now. Check them for water, chances are the smaller containers will need a daily soaking while larger ones may last a couple of days. This also depends on if they’re located in sun or shade, or in a windy location. If you are going away for even a long weekend, make plans to have someone water them.

By August any fertilizer in the potting mix will have been used up so, if you haven’t already, start weekly feedings of a liquid fertilizer to help them keep those beautiful flowers and leaves coming.

Rearranging Perennials

Perennial flower gardens come in and out of bloom all summer and avid gardeners enjoy the challenge of trying to have something in bloom throughout the summer. August is not a good time to divide or replant them but I do find it’s when I get the most ideas of where I’d like to move certain plants later on.

Take photos of your garden every couple of weeks and make notes of where you need a different color, something taller or wider, a different leaf texture, and so on. It is surprisingly difficult to remember where those spots were come next spring when you’re ready to do some digging and moving! Some gardeners have luck moving early summer blooming plants in early September when the plant is in a quieter state, not busy producing its annual flower show.

Keep on Deadheading

A lot of gardeners are ready to take a break by mid-August, after having spent the previous 3 months diligently weeding, mulching, and watering. But don’t give up on your annual flowers yet!

Zinnias, calendula, cosmos, ageratum, snapdragons, marigolds and more will stop flowering if you let them go to seed. Keep snapping off the faded flowers or better yet, keep cutting the flowers for bouquets to keep them from going to seed.

Calendula thrives in the cooler temperatures of September, so I often prune them back quite hard in August in order to push out lots of new growth that will flower well into the fall. They can easily take a light frost.

Zinnias and ageratum are some of the most sensitive to frost, so keep making bouquets of these to enjoy as much as possible this month while they are at their peak.

Photos: Above, Cornell University Horticulture Professor Stephen Reiners talks with growers in Northern New York (courtesy Amy Ivy, CCE Clinton County); and below, ageratum (courtesy gardening.cornell.edu).