It is that time of year when we all wait for our tomato plants to produce ripe and succulent fruit. But here in northern Nevada it seems that there is always something preventing us from enjoying the fruits of our labors.
One of the biggest questions we get is “why aren’t my tomatoes ripening?” Each variety of tomato has its own time to maturity, usually mentioned on the tag of the plant you purchase or on the seed packet. Days to maturity can vary from 55 to 100, so different tomato varieties will produce fruit at different times. Tomatoes are a little fussy about temperature. If it is too cold at night or too hot during the day, tomatoes will stay on the vine fully ripe, but not turn red. Tomatoes ripen best at temperatures between 70-75 degrees F. If you pick tomatoes that have a slight blush of pink color and put them in the house on the counter, they will turn red in just a few days. Another reason your tomatoes may not appear to be ripe is that they may not be red tomatoes. Many new varieties are pink, orange, yellow and even green. Check your plant tag for the mature color of the specific varieties you planted.
Here are some common tomato afflictions, not related to insect pests or disease, but the result of inconsistent irrigation and inadequate plant leaf cover.
Sunscald: Fruits develop yellowish or whitish patches on the side of the fruit exposed to the sun. The patches turn leathery and dry out. Fruit on the same plant that is protected from sun by shade or leaf cover is unaffected. Use row covers to provide shade for small areas. Select varieties next year noted for good leaf cover.
Green or Yellow Shoulders: Fruits develop discolored green or yellow shoulders on otherwise ripe fruits as a result of high temperatures. Similar to sunscald, these areas never ripen and are tough and inedible. Providing shade and choosing varieties for good leaf cover can help prevent the problem.
Radial Cracking: Fruits develop large cracks radiating out from the stem attachment. Cracking occurs on both red and green fruit. Prevent wide swings in moisture by providing even irrigation and mulching. Select varieties that are more crack-resistant.
Cat-facing: Tomatoes develop that are misshapen with scars and holes at the blossom end of the fruit. The cause is thought to be cold weather during blossoming and perhaps high levels of nitrogen. Avoid setting out transplants too early, and avoid over-fertilizing.
Blossom End Rot: The blossom end of the fruit fails to develop normally, turning black to dark brown. Blossom end rot is usually due to fluctuations in temperature and irrigation. Even though our soils contain plenty of calcium, inconsistent irrigation prevents its transport up to the fruit causing a calcium deficiency.
We’d all like our tomatoes to be pretty and tasty. For all of the tomato problems mentioned, except blossom end rot, the unaffected portion of the fruit remains edible.
Melody Hefner is the Urban IPM and Pesticide Safety Education Program Assistant for University of Nevada Cooperative Extension. For more information on gardening in northern Nevada, attend our Grow Your Own, Nevada! classes held 6-8 p.m., Tuesdays and Thursdays, September 1-24. Have a gardening question? Ask a Master Gardener at firstname.lastname@example.org or visit www.growyourownnevada.com.