Tomato Problems

By Pat Curran

Question:

I have spotty leaves and green tomatoes, not red ones .  How can I do better next year?

Answer:

Despite being a favorite ‘vegetable,’ tomatoes have their problems.  Recently, late blight was reported in the area of Rt. 79 east, and then at the Cornell research farm near Freeville.  Late blight fungus was responsible for the Irish potato famine that killed a million people and caused many to emigrate, rather than starve.  It destroyed the storage potatoes as well as the plants in the fields.

late blight
Phytophthora infestans
Gerald Holmes

Several years ago, we had an outbreak of late blight that was atypically early, due to infected tomato transplants at the big box stores.  Normally, late blight appears later in the growing season.  It can wipe out farm fields of potatoes and tomatoes, as well as home gardens.  Usually late blight overwinters only on living plant tissue such as potatoes left in the ground.  It will not overwinter on frozen tomato plants, stakes, labels, or in the soil itself (yet).  However, it is important to remove infected plants so as not to spread the disease.  

Cornell researchers are hard at work, developing tomatoes varieties resistant to late blight.  Several Tompkins County Master Gardeners are trialing ‘Iron Lady’ tomato this year.

So what about early leaf spots?  Early blight and septoria are two fungus diseases that typically appear earlier in the season.  These fungus diseases DO overwinter in the soil, so we recommend crop rotation.  Tomatoes and potatoes are in the same plant family, so that is not a true rotation.  For a list of vegetable plant families, please contact the GrowLine horticultural hotline for “Rotating Plants by Family.”

Septoria on Tomato

Paul Bachi

Other tomato problems include fungus diseases, verticillium and fusarium, and nematodes.  Many tomato varieties are labeled ‘VFN’, indicating resistance to these problems.  Heirloom tomatoes may or may not have resistance, but seed companies don’t usually run tests to determine this.

Another frequent tomato problem which we don’t seem to have this year, is blossom end rot.  This black blotch at the bottom of the tomato is caused by a calcium deficiency, which in turn is caused by uneven watering, which impairs calcium uptake by the roots.  We see it more in dry years when gardeners either don’t water enough or often enough, or don’t apply mulch.  If I plant deeply in my clay soil amended with organic matter, and mulch with rotten leaves, I never see blossom end rot.

Cool nights are to blame for the lack of ripe tomatoes this year.  Try draping row cover over the plants to trap and retain some more heat.  Let’s hope for warm weather in September!

Ask a Gardener appears weekly in The Journal during the growing season. For answers to other garden, lawn, landscape and pest questions, call Cooperative Extension at 607-272-2292 or email: growline1@gmail.com. This article was written by Patricia Curran, horticulture program manager at Cornell Cooperative Extension of Tompkins County. 

August Gardening Update

By Pat Curran

Question:

What’s doing well in our area this summer?

Answer:

The only consistent thing about upstate NY weather is its inconsistency!  After several overnight temps in the lower forties, here’s a report on veggies and flowers.

Tomatoes are slow to produce and ripen this summer.  Here’s the latest from Cornell plant pathologist Tom Zitter (via e-mail Tues. evening).  He reports tomato late blight that he observed in his garden just off Rt. 79 in the Town of Ithaca.  He advises homeowners to harvest any fruit that is starting to show color, unless they plan to spray, or they are growing the new resistant varieties.  There will be “perfect conditions for late blight” due to the cool damp weather.

late blight
Phytophthora infestans
Gerald Holmes

Although tomatoes have been producing barely enough for a couple of salads each week, some adjacent veggies (growing in large containers in the hottest, sunniest exposure available at my cool country location) have surpassed expectations.  ‘Swallow’ eggplant is a slender purple eggplant that never gets bitter.  The first fruit arrived around July 10^th, and the plants are loaded with more.  This is also a very attractive plant, suitable for mixing with ornamentals, with its purple-flushed foliage and large purple flowers.  Cover the young plants with row cover until they get big enough to outgrow fleabeetle damage. 

 ‘Jimmy Nardello’ sweet pepper is an heirloom skinny frying type that appears to ignore cool nights.  Even last year when planted in the ground, it produced lots of peppers for freezing.  Basil is growing well, also in containers (I like to take a few plants in for growing at a sunny windowsill during the winter).  The okra?  Lots of flowerbuds, but little fruit set so far.  The broccoli in the veggie garden looks good.  This would have been a good season to plant snap peas late in May, but I didn’t because they fade away in hot weather.  Had I known!

As for flowers, daylilies are blooming longer than usual, as they tend to do with lots of moisture.  Perennial phlox and beebalm also appreciate the extra rain.  Cardinal flower is in bloom now in damp light shade.  Clethra, summersweet, a fragrant and very adaptable native shrub, is flourishing too.  Look for the pink variety ‘Ruby Spice.’

hydrangea
Hydrangea spp. 
Photo by Karen Snover-Clift

Hydrangeas are looking good, if they are the types that bloom on the current season’s growth.  ‘Quickfire’ is an earlier-blooming paniculata hydrangea with pinker blooms; ‘Limelight’ blooms a little later with green-tinged clusters.  ‘Annabelle’ and pink ‘Invincibelle Spirit,’ cultivars of the native Hydrangea arborescens, are very handsome.  Hydrangeas that carry their flowerbuds on last season’s growth may have been killed to the ground by last winter’s weather – so no flowers this year.

Ask a Gardener appears weekly in The Journal during the growing season. For answers to other garden, lawn, landscape and pest questions, call Cooperative Extension at 607-272-2292 or email: growline1@gmail.com. This article was written by Patricia Curran, horticulture program manager at Cornell Cooperative Extension of Tompkins County.