The Yellow Farmhouse Garden

By now if you have tomatoes in your garden, I’m sure you have been seeing leaves that have started to turn yellow and develop spots.  These are symptoms of any one of three fungal diseases that infect tomato plants in our area; Early Blight, Late Blight and Septoria Leaf Spot.  They are often referred to by many gardeners as just “Tomato Blight”.

Early Blight spots usually form concentric rings as the spots get bigger.  Late Blight Spots have less distinctive borders and often look watery, while Septoria Spots appear smaller and separated.

Blight on my tomato plant, can you guess which one it might be?

Early Blight and Septoria are the most common and  show up very frequently  in tomatoes, so much so that many gardeners accept this as a normal part of tomato growing.  Late Blight is a much more serious infection.

Late Blight and Early Blight will infect the fruit as well as the leaves while Septoria will cause reduced yields and damage from sun scald due to lack of leaves available for photosynthesis and to protect the fruit from the direct rays of the sun. Late Blight can be particularly damaging as it can kill an entire garden full of tomatoes in 10 days if the weather conditions are right

The treatment is about the same for all three diseases: spraying the plants with a fungicide.  The treatment will not “cure” the disease but will help keep the symptoms from progressing further. Be aware that you need to be vigilant in applying your fungicides if you decide to spray.  Rotation of your planting from year to year helps somewhat if you have the space to do so.  Dead and dying plants should be removed and bagged up and be sent to the landfill along with your regular trash to avoid spreading the diseases.

Michigan State University has a good Fact Sheet that discuses these diseases in more detail.

These Blights will also infect Potatoes which belong to the same plant family as  tomatoes.

Bob

While walking through a friend’s garden last week, I noticed a problem just getting started in her cucumber vines.

The leaves were beginning to show signs of Downy Mildew, a fungal disease that often plagues cucumbers. If left untreated, the disease can defoliate an entire crop in just a few days. The developing fruit then become stunted and sun scalded because no leaves are left to provide growing energy for the cucumbers or protection against the direct rays of the sun.

Downy Mildew can be recognized by the appearance of light-green spots on the surface of the leaves. A couple of days later the spots turn yellow and angular following the pattern of the veins on the leaf. The yellow spots die back and turn brown eventually killing the entire leaf.

The yellow spots enlarge and follow the outline of the veins in the leaf.

Spraying a broad spectrum fungicide can help control the disease. There are several conventional and organic sprays out there to choose from.

Today I spotted early signs of Downy Mildew  on my cucumbers. I treated it with a potassium bicarbonate product I found last year. I have never used this product but I’ll let you know how it works.

This disease develops more rapidly during periods of high humidity and moisture. By watering your plants early in the morning, you give the excess water time to dry off of the leaves. Watering late in the day keeps the plant from drying completely and creates a humid environment for the disease to progress.

It’s a little late for this season but keep in mind when ordering seeds for next year that some of the newer varieties are resistant to Downy Mildew.

Downy Mildew will attack zuccini and other types of squash as well as melons and other related crops.

Bob