Fertility Advice From The Greenhouse Tomato Short Course

Joe Kemple

The 22nd annual Greenhouse Tomato Short Course has now come and gone. Participation was excellent this year, with growers from coast to coast in the U.S., as well as all the way from Brazil, the Bahamas, Trinidad,  Tobago, and Ghana!  

If you have never come to Mississippi for this national conference designed for greenhouse tomato growers, check the web site for information:

While there was too much presented during two days of seminars for an article like this, I’d like to focus on some nutrition and fertility information presented by Dr. Joe Kemble of Auburn University.

Mobile Elements

First of all, an understanding of how mobile elements are is important to trying to figure out which nutrient deficiencies your tomato plants may have.

Mobile elements — those that move easily within the plant from older growth to newer growth — include nitrogen, potassium, and magnesium.

Why is this important? If there is not enough of one of these elements in
the fertilizer solution, the older leaves will show deficiency symptoms first. Older leave are those at the bottoms of plants, as well as those half way or so up the plant.

On the other hand, iron is considered to be an immobile element. It will not move very much from older to newer leaves. Symptoms of not enough iron will show up first in the newer leaves, i.e. at the tops of the plants.

Calcium is the problem child. It is mobile — sort of. If the youngest parts of the root system are active and healthy, they will take up calcium and it will travel throughout the plant. If, however, there are any stressors on the plant that slow down these young roots from growth, calcium uptake is limited and deficiency symptoms will be evident. Calcium is taken in mostly through the very young roots and not much by older roots.
Look For Symptoms
With nitrogen, a general light green or greenish yellow coloration indicates deficiency. This will start with the older leaves, but can progress upward to include the whole plant if it continues unchecked. Deficiency also produces “leggy” plants, with thinner stems and longer internodes, and some purpling may show up on the undersides of leaves.

Low potassium will show up as necrotic (dead, brown) spots on the older leaves. The spots are interveinal — between the veins; veins remain green.

These will progress inward toward the main stem, and also upward toward new growth. Potassium symptoms may also show up as yellowing margins (edges) of the leaves. Fruit symptoms include whitish, unripe areas inside the fruit, and softening of fruit tissue.

With lack of magnesium, a pronounced interveinal chlorosis (yellowing) of older leaves is very evident. While veins remain green, the yellowed tissue between veins becomes very prominent. Sometimes the margins remain green. Often, this occurs about half way up the plant shortly after the fourth cluster has set fruit. This is probably the most common deficiency
in tomatoes grown in the greenhouse.

Since iron is immobile, a limitation will cause it to remain in the old growth and cause symptoms at the tops of plants. This occurs as interveinal chlorosis in the young leaves. Unique with iron is that the yellowing starts at the bottom of leaflets, and then progresses upward until the whole leaflets will be yellow or even whitish in severe cases. Veins normally remain green.

This occurs when iron in the fertilizer is too low, but can also happen if the growing medium is kept too wet or even waterlogged.

Prevention, Diagnosing Problems

A tissue analysis is probably the best single thing a grower can do to detect nutritional problems even before there are symptoms, or to diagnose a problem after it occurs. While there is a fee for testing, a biweekly schedule is advisable and not too expensive to keep plants healthy. Either a testing lab at your state university or a commercial analytical lab can be used. Test results will help growers decide how to make changes in the fertilizer program. 

Leave a Reply

Featured Stories

All Vegetables Stories >All Fruits Stories >All Nuts Stories >All Citrus Stories >

The Latest

CitrusHarness The Marketing Power Of Video
September 1, 2014
Multimedia platform is an effective and inexpensive marketing tool for you to attract new customers and keep existing ones loyal to your brand. Read More
Citrus Achievement AwardDespite Industry Challenges, Florida Citrus Leader Has …
September 1, 2014
2014 Florida Grower Citrus Achievement Award winner Mike Sparks feels confident in crop sector's ability to regain strength. Read More
Florida Ag ExpoFood Safety Modernization Act Is On The Plate
September 1, 2014
Florida Ag Expo agenda to serve up important features of looming regulations. Read More
CEU SeriesCEU Series: Put Weeds Out To Pasture
September 1, 2014
No matter where they are, plants out of place can be problematic. Read More
TomatoesProduction Reaches An All-Time High For Processing Toma…
August 29, 2014
A record high is predicted for the 2014 processing tomato crop. Read More
CitrusFlorida Department Of Citrus Knocks NPR Piece Over Juic…
August 28, 2014
Agency goes to bat for the industry regarding statement slighting OJ's health benefits. Read More
Disease ControlLate Blight Update Reveals Heightened Activity
August 28, 2014
While several states in the Northeast have confirmed the presence of late blight, the disease has not been reported in North Dakota or Minnesota. Read More
CitrusFlorida Energy Firm Charged Up About Citrus Biomass Pot…
August 28, 2014
Machine called a game-changer when it comes to a cost-effective, efficient way for tree removal and re-purposing. Read More
EquipmentNew Tractors Improve Maneuverability And Operator Contr…
August 28, 2014
The Magnum Rowtrac tractors from Case IH meet growers’ cropping needs through a wide variety of row spacing and belt options.   Read More
NutsCalifornia County Passes Ordinance To Protect Walnut Gr…
August 27, 2014
Verification of ownership needed to complete sales of valuable nuts. Read More
NutsAlmond Growers Hit By Russian Import Limits
August 27, 2014
Growers reflect on changes to export market in light of produce ban. Read More
Farm ManagementLeadership And Management Expert To Speak At California…
August 27, 2014
Daniel Goleman will make presentation at California State University-Fresno. Read More
CitrusNational Scientific Summit On Herbicide Resistant Weeds…
August 27, 2014
Topics to be covered include the economics of proactively managing herbicide resistance, education and outreach efforts, and incentives and regulatory initiatives. Read More
FruitsFlorida Organic Group Dedicated To Serving Growers, Com…
August 27, 2014
Education and development programs are plentiful for interested producers. Read More
VegetablesExperimental Herbicide Technology Blasts Weeds In Rows
August 27, 2014
The technology uses an air compressor to spray corncob grit on both sides of a crop, killing young weeds. Read More
Disease ControlFungal Disease Outbreak Hits Pacific Northwest Vegetabl…
August 27, 2014
An outbreak of blackleg, light leaf spot, and white leaf spot can be significant problems in several vegetable crops.   Read More
CitrusClean Water Conundrum: Ditch The Rule Or Ditch The Myth…
August 26, 2014
Regulation inundation causing a rising tide of confusion for farmers. Read More
BerriesMichigan State University Extension Offers Tips To Prev…
August 26, 2014
Humidity, rainy periods conducive to disease development. Read More