June 18, 2016

1 - The heat of New Mexico summers can prevent fruit from forming on some varieties of tomatoes until the weather cools.

Yard and Garden June 18, 2016

Q.

I read the article about growing tomatoes in soil versus containers on Sun-news last week. It is very interesting! I also have a problem about my tomatoes. I have been growing tomatoes for last two years since we moved here. But I cannot grow tomatoes well here. One big problem is they do not produce tomatoes after flowering. The flowers are either wilted or dropped. At first, I thought maybe it is too hot and they need more water. I started to water more. But still, they do not produce. Do you know what the problem is? Can I do anything to help them to produce?

- Y.

Las Cruces

A.

Tomatoes are a favorite garden vegetable, but in New Mexico they can be somewhat challenging. There are several factors that result in failure of the tomato plants to form fruit.

One common factor is that many varieties (the larger fruited varieties in general) cannot set fruit in hot weather. The pollen is killed by the heat and cannot successfully pollinate the flower. Or, the generative nuclei of the pollen are unable to move from the stigma (where pollen is received) through the style (stalk connecting stigma to the ovary). Failure of the generative nuclei to successfully move from stigma to ovule (and failure to have viable pollen) results in failure of the generative nuclei to fertilizer the egg cell in the ovary. As a result no fruit will form. When the weather is cooler, as may perhaps occur, after monsoon rains begin, the fruit may begin to form. Many years ago some new varieties of tomato were bred by Texas A&M to form fruit in the heat of summer. 'Saladette' was one of the first of these. I have noticed several varieties in the nurseries with names that imply that they will form fruit in the heat. I have tried some of these with some success. I have also had success with 'Heritage' an older variety. These form medium sized tomato fruits that are big enough to be good with sandwiches and salads. The really large "beefsteak" types tend to delay forming fruit until late summer and into the autumn. Cherry and pear tomato plants produce small fruit that are good for salads and other meals where small size is not a problem. These smaller types tend to successfully form fruit even during the hot part of summer. Experiment with several varieties, especially those known to produce fruit in the heat. You may find varieties that work well in your garden environment.

Another trick is to shade the plants to reduce the heat the plants receive. Tomatoes need about 4 to 6 hours of sunlight each day, but light shade, especially in the hottest part of the day (afternoon) will increase the chances that the tomatoes will produce fruits for you.

Some gardeners have problems with tomatoes because they are too generous. These gardeners tend to over fertilize their plants. Excess nitrogen fertilizer (the first number on a fertilizer bag) causes excessive growth. The plants look healthy and grow wonderfully, but they produce few flowers and no fruit. Addition of additional phosphate fertilizer to the side of the plants may help them form fruit. Phosphorus is a mineral that encourages flowering and fruit formation in plants. (Phosphate is the second number on a fertilizer bag.)

Avoid growing tomatoes and related plants (eggplant, chiles, and such) in the same location each year since they deplete the nutrients and may result in accumulation of disease organisms specific to these plants in that area. Alternate tomatoes with beans, corn, squash, and other non-solanaceous crops (tomatoes are in the plant family Solanaceae).

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

Links:

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