NEIGHBORHOOD GARDEN FOR AUGUST 9, 2008

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TOMATOES

BY GEORGE EDGAR

          This is the first in a series of articles sharing some of the practices I use in my garden and other tips that I have picked up along the way. Where possible I will include why I do what I do, facts about plants, and how they grow and develop. This first one is about:

TOMATOES:

·        Do not plant your tomatoes too early. If the soil temperatures are too low they will just sit in the garden and not grow. If it is wet like this last spring, they may rot. I never plant mine before May 15th. I may not have the first tomato but they grow fast.

·        Tomatoes are unique in that roots will grow from the stems if planted deep. Sometimes I will deliberately get “leggy” tomatoes from the garden center and then plant them very deep so I have only a few leaves at the top. These plants resist drought because of the deep root system and the stocks will be stronger and straighter than if I planted it at the depth it was growing in the small pot. Last fall some of my tomatoes had roots 12 to 14 inches deep when I cleaned up the garden.

·        I add 10-10-10 slow release granular fertilizer to the soil when planting tomatoes. This fertilizer lasts for three months so makes it easy. I add more fertilizer about August 1st and they grow tall and produce until frost. Do not over fertilize with nitrogen or you will have beautiful plants but no flowers and fruit.

·        I made good strong tomato cages from wire fencing used to reinforce concrete driveways and streets. This fencing is usually 5 feet tall and I use a 5 foot piece for each cage. You can bend the end over to secure the cage or tie together with a piece of wire. My tomatoes are usually very tall so I have to use at least two pieces of rebar pounded into the ground and then attached to the cage to keep the wind from blowing them over. This gets the tomatoes up off the ground and away from some insects and diseases.

·        I use the stretchy “TIE TAPE” to tie the plants to the cage or the whole plant will collapse under the weight of the tomatoes when they get tall and large.  

·        Between the cages I put 5 to 6 layers of newspapers to keep the weeds down. Newspapers are made from wood pulp and most use soy ink so they can be tilled into the soil at the end of the season. Dirt, grass clippings, straw, compost, coffee grounds, etc. can be used to cover the newspapers so they do not blow away.

·        I do a number of the things above because the tomato blight pathogens are in the soil. When my tomatoes get about 3-4 feet tall, I prune off the lower 8-10 inches of leaves and stems. This gets the leaves up and off the ground so the pathogens are not splashed up on them. Also it opens the plant for good air flow up through the plant. Leaving plants on the ground only encourages insect and disease problems.

·        Remove all blight infected leaves from the plant immediately to help control spread of disease. Also remove the leaves from the garden and do not compost. This year with all the spring rain, one plant really got infected and I have very few leaves left. Since I had to remove so many leaves, some of the tomatoes have sun scald. I will now cover the cages with row cover, cheesecloth, or weed barrier to shield the tomatoes.

·        Rotate where you plant tomatoes. I have enough space that I grow tomatoes in the same location for two years and then move on to another row. Potatoes and egg plant are in the same family so don’t rotate with these crops. Do not return to the same location for at least three to four years.

·        Tomatoes do not need insects for pollination, contrary to popular belief. As with some other vegetables and other plants the flower is a perfect flower which means it has both male and female parts in each flower. These plants do need wind or movement to transfer the pollen from the male part to the female part. Hormones and other sprays, such as Blossom Set, does not increase pollination, according to a study at Iowa State University. A friend, who interned in California, said he saw many helicopters flying low over the fields of tomatoes on a regular basis to create winds to increase the pollination. In a greenhouse they go around with a small tool that looks like a toothbrush and vibrate the plants to insure pollination. Insects can pollinate tomatoes but are not necessary.

·        According to Dr. Laurie Hodges, Vegetable Specialist, Department of Agronomy and Horticulture at University of Nebraska-Lincoln, “A lot of research has been done on tomatoes and especially fruit set in tomatoes. Day temperatures over 90 degrees F. and night temperatures over 70 degrees F. reduces fruit set. As few as 3 hours at 104 degrees F. on two successive days may cause failure of fruit to set.”

·        She also says, “Tomatoes use more water than any other vegetable in the garden when full grown and laden with fruit. A tomato is 95 % water and it takes about 8 gallons of water to grow one tomato.” How much water per week “depends on the size of the plant, the soil type, the stage of growth, the air temperature and relative humidity. Although tomatoes use a lot of water, in the right soil type, they can have very deep root systems which contributes to drought tolerance.”

·        When watering do not overhead water unless you have to. This will reduce the pathogens splashing onto the lower leaves. Also do not overhead water after 2:00 pm in the afternoon. Most disease pathogens need a drop of water on the leaf going into the evening in order to inoculate the plant. This is true with every plant including grass, annuals, perennials, shrubs, trees, etc. Let the leaves dry before night.

 

Reference: “From Farm to Market”, Volume 14, Number 3, July 2005. Edited by Dr. Laurie Hodges, Vegetable Specialist, Department of Agronomy and Horticulture, University of Nebraska-Lincoln: pages 4 and 5.

Copyright 2008