 Christmas trees
Field Crops
Fruit
Home and yard
Nursery and landscape
Turfgrass
Vegetable
Diagnostic Services
Soil/Plant Nutrient Lab
Ag weather
Regional IPM Center
Pesticide safety
Organic: New Ag Network
Invasive species
Sustainable ag & food systems
MSU ANR departments
MSU Extension
Site index
Contacts/permissions |
|
 |
No. 10, May 10, 2007
|
|
 Selecting which iron chelate to use
MSU Garden Plant Showcase – August 7
Check out MSU’s Landscape Alert newsletter
This is the final issue for the season. See you in December 2007! |
|
|
Dean Krauskopf
MSU Extension, Southeast Michigan
Plants take up nutrients only when they are in solution, which can be a problem with iron.At pHs above 6.5, interactions with calcium and other ions in the media solution cause iron to precipitate out of solution and become unavailable to plants.Using iron chelates can keep plants green and growing until you can drop the pH to proper levels.
Chelates can best be visualized as a lobster’s claw (appropriate since the word chelate comes from a Greek word meaning claw) made of carbon and hydrogen atoms holding an iron ion. The more bonds, called ligands, that form between the iron ion and the carbon atoms, the stronger the iron ion is held within the chelate.The strength of the chelate’s hold on the iron ion determines, as pH increases, how long the iron ion will continue to be in solution and therefore available to plants.
There are four commonly used chelates: citric acid, EDTA (Ethylenediaminetetraacetic acid), DTPA (Diethylenetriaminepentaacetic acid) and EDDHA (Ethylenediamine di(o-hydroxyphenylacetic acid)). According to data presented by Norvel (Equilibria of Metal Chelates in Soil Solution, in Micronutrients in Agriculture, Soil Science of America, 1972) citric acid does not strongly bond with iron and is not effective at pHs above 6.0. EDTA strongly holds iron in solution up to pH 6.0, but by pH 6.5, almost one-half the iron is precipitated, and by pH 7.0, almost none of the iron is available to plants.DTPA is an excellent iron source up to media pH 7.0; however, 60 percent of the iron is precipitated and unavailable by pH 8.0. EDDHA is the strongest chelate of any of the commonly used materials and maintains iron availability to plants past pH 9.0. These chelates are ranked in the same order of effectiveness by Drs. Bill Argo and Paul Fisher in Understanding pH Management, Meister Publications. |
|
Chelates prove the maxim “You get what you pay for.” The cheaper the chelate, the less useful it is.You may have to sit down when you write the check for iron-EDDHA, but remember you use very little per plant and you are assured that iron is available to your crop no matter the pH.
Here’s a related topic.Sometimes growers are puzzled by plants showing iron deficiency symptoms when the media pH is only slightly higher than desired.Phosphorus ties up iron and the combination of a weak chelate, slightly high pH and high phosphorus levels can cause iron to be unavailable.Another reason not to over apply phosphorus. |
| back to top |
|
Erik Runkle and Norm Lownds
Horticulture
Greenhouse growers, garden center retailers, and landscapers are invited to the 2007 MSU Garden Plant Showcase on Tuesday, August 7.This event includes self-guided tours of the MSU Demonstration Gardens that feature nearly 1,000 different cultivars, direct comparisons of performance in ground beds and in containers, and new this year, evaluation of Cool Kid Plants.When you visit MSU, be sure to plan enough time to see the Perennial Display Garden, Rose Garden, 4-H Children’s Gardens, Clarence E. Lewis Landscape Arboretum, and the Ornamental Grass plots.
In addition, several presentations will be delivered by MSU faculty and staff that focus on new plant material, a review of some of the greenhouse production challenges in the state this year, and two exciting presentations specifically for garden plant retailers.The featured speaker is Dr. Art Cameron, who starts the program with a photographic journey to visit some of his favorite “new” plants – new to science, new to the industry, or just new to Art.
The $35 advance registration fee includes a trials booklet to facilitate your own tours of the gardens, admission to the educational programs, lunch, and a parking pass.For more information, please visit www.hrt.msu.edu/planttour/MSU_showcase.htm.Advance registration ends on July 23. |
| back to top |
| |
Joy N. Landis, editor
This is the end of season for the Greenhouse Alert newsletter; however, many readers will find items of interest in our Landscape Alert newsletter. To access past issues, visit: http://www.ipm.msu.edu/land-cat.htm
The Landscape Alert addresses pest management and plant care for a wide ranging audience that includes nurserymen, commercial landscapers, turf managers, master gardeners and Christmas tree growers. Here is a list of contents in the May 4, 2007 issue:
Landscape and nursery
Neighborhood walk indicates early season damage
Winter damage to roses and boxwood
Downy mildew control on roses
Scouting for weeds: henbit and purple deadnettle
Turfgrass
Thinking about treating for grubs?
Miracle weed and tips for seeding turf
Christmas trees and forestry
Time to manage needle cast diseases of Douglas fir and spruce
Insects to scout for week of May 5
Christmas tree and forestry insect update
Update on gypsy moth spray window dates
Around the home
Pests of boxwood
Tick season arrived early this year!
What to do about moles
Other news
Ecological Restoration Field Day: June 15
Weather news
You can sign up to get an email announcement for the Landscape Alert similar to the one you receive for the Greenhouse Alert at: http://www.ipm.msu.edu/email-landscape.htm |
| back to top |
| |
|
|
