Gardeners love tomatoes. We buy unusual varieties, as well as old dependable standards. We spend hours and hours tending our plants in hopes of luscious fruit. We pamper them with specialty fertilizers. We hope for good weather, not too hot and not too cold, so that fruit will not only set, but also ripen.
So, why aren't some tomato plants producing fruit? You may be seeing a lot of flowers and vigorous, thick foliage, but no tomatoes. Poor fruit set can occur for a number of reasons.
Temperatures have been very hot. We don't like it and neither do our vegetables. Extreme temperatures, including extended periods above 90 degrees or below 55 degrees (we wish!), will make blossoms drop off plants without setting fruit. Dry soil will also cause blossoms to dry up and fall off. Plants that are in the shade and receive less than six hours of sunlight a day will also fail to set fruit. Finally, using a fertilizer with too much nitrogen will encourage a lot of leaves, but no fruit.
There isn't too much you can do about the heat, except for shading plants during the hottest part of the day. However, it is very labor intensive to set up and remove shade structures each day. You can control your irrigation. Don't allow the soil to dry out. Mulch the tomato bed with organic matter, such as straw, mulch, compost, grass clippings or leaves (but nothing contaminated with weed killer). Fertilize with a vegetable food low in nitrogen, with the first number of the fertilizer ratio listed on the bag being relatively low, such as 8-10-8 or 10-10-10.
You may also be seeing brown-black patches on the bottom of your ripening tomatoes. This is blossom end rot. It is a physiological disease, one that is not caused by a microorganism. It involves calcium nutrition and water balance. This condition is aggravated by high salts in the soil or low soil moisture. It is quite common in gardens with sandy soils. The solution is to maintain even soil moisture. If a particular variety you have planted is susceptible, make a note and buy a different variety next year. Some varieties are more affected than others.
Another physiological disorder is catfacing. With this condition, the fruit looks deformed and twisted, but it is still edible. We shouldn't be seeing too much catfacing because it is caused by cool and cloudy conditions at bloom time. If you do find your tomatoes suffering from this, try a different variety next year.
In the end, we will still end up with green tomatoes when the first frost hits, so be sure to stock up on green tomato recipes!
For more information, e-mail skellyj@unce.unr.edu or call me at 887-2252. You can "Ask a Master Gardener" by e-mailing mastergardeners@unce.unr.edu or call your local University of Nevada Cooperative Extension office. Check out many useful horticulture publications at www.unce.unr.edu.
• JoAnne Skelly is the Carson City/Storey County Extension educator for University of Nevada Cooperative Extension.