This time of year means ,for sure, there will be something on your kitchen counter; TOMATOES!!!
Tomatoes Slow to Ripen?
The extremely hot weather we have had recently not only interferes with flower pollination (see July 11 newsletter) but also can affect how quickly fruit matures. The best temperature for tomato growth and fruit development is 85 to 90F. When temperatures exceed 100 degrees, the plant goes into survival mode and concentrates on moving water. Fruit development slows to a crawl. When temperatures moderate, even to the low to mid 90s, the fruit will ripen more quickly.
Tomato color can also be affected by heat. When temperatures rise above 95 degrees F, red pigments don’t form properly though the orange and yellow pigments do. This results in orange fruit. This doesn’t affect the edibility of the tomato, but often gardeners want that deep red color back.
So, can we do anything to help our tomatoes ripen and have good color during extreme heat? Sure, there is. We can pick tomatoes in the “breaker” stage. Breaker stage tomatoes are those that have started to turn color. At this point, the tomato has cut itself off from the vine and nothing will be gained by keeping it on the plant. If tomatoes are picked at this stage and brought into an air-conditioned house, they will ripen more quickly and develop a good, red color. A temperature of 75 to 85 degrees F will work well. (Ward Upham)
Tomatoes often have problems with cracking caused by pressure inside the fruit that is more than the skin can handle. Cracks are usually on the upper part of the fruit and can be concentric (in concentric circles around the stem) or radial (radiating from the stem). We don’t know everything about cracking but here is what we do know.
Tomatoes have a root system that is very dense and fibrous and is quite efficient in picking up water. Unfortunately, the root system can become unbalanced with the top of the plant. Early in the season it may be small in relation to the top growth resulting in blossom-end rot during hot dry weather. Later it may be so efficient that it provides too much water when we get rain or irrigate heavily after a dry spell. This quick influx of water can cause the tomato fruit to crack. Therefore, even, consistent watering can help with cracking. Mulching will also help because it moderates moisture levels in the soil. However, you can do everything right and still have problems with cracking in some years.
We have evaluated varieties for cracking during our tomato trials at K-State. It takes several years worth of data to get a good feel for crack-resistant varieties but we have found some real differences. Some varieties crack under about any condition and others are much more resistant. The difference seems to be pliability of skin rather than thickness — the more pliable the skin the more resistance to cracking.
The old variety Jet Star has been the most crack resistant of any we have tested including the newer types. Unfortunately, Jet Star is an indeterminate variety that puts out rampant growth.Newer varieties with more controlled growth are often more attractive to gardeners. MountainSpring, Mountain Pride, Mountain Fresh, Floralina and Sun Leaper are smaller-vined types thathave shown good resistance to cracking. (Ward Upham)
Extreme heat and bright sunlight can sunscald tomato fruit, leaving a light yellow to white
sunken spot that resembles a blister. Eventually this area may allow black mold in invade and cause the tomato to rot.
Sunscald most often happens to fruit that is exposed to full sun after losing foliage to disease, hail or tomato hornworms. Exposed fruit may be shaded with cheesecloth to prevent injury. Fruit can also be harvested as the tomato starts to turn color so they can ripen inside. Tomatoes picked at this stage will be just as sweet as those left to ripen on the vine. Remove affected fruit to encourage more fruit set.
Sunburned fruit are rarely usable if the damage is extensive. Tomatoes with little damage can be used if sunscalded areas are cut out. (Ward Upham)