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Chemigation is the delivery of chemicals, including insecticide and fertilizer, via irrigation. Fertigation is a more restrictive term describing the delivery of fertilizer. The methods are now routine in agriculture, but their full potential is still being explored for trees and landscapes.
The advantages of applying chemicals through irrigation are obvious. Injector systems can be precisely calibrated to put down proper amounts on a controlled schedule. Fertigation has produced good results on turf and with shrubs and annuals because it can deliver small amounts with every watering. That keeps plants lush and green for the long term.
Most trees, however, do well fixing nutrients from their own soil. The delivery of nutrients at a constant rate is less critical for their success. One exception to this rule is palm species, which frequently require mineral supplements.
When it comes to trees, the deep and frequent application of water is more critical. This is why drip and bubbler systems have met with such success.
The other big advantage, of course, is water savings. Because of the way the water is applied in a drip system, traditional surface applications of fertilizer can be ineffective. That?EUR??,,????'?????<
A less-explored frontier is using irrigation to send a stream of pest-control chemicals to trees that need it. If successful, the method might provide a welcome alternative to micro-injection, sprays and soil drenching. In fact, some recent research has delivered promising results.
Recent work on irrigation-delivered imidacloprid in grape vineyards (for vine mealybug) and ornamental ash trees (for emerald ash borer) suggests that chemigation holds promise for control of these and other pest species, a team from Utah State University reports.
As said above, fertigation for turf and shrubs is a well-understood science.
A number of products exist along with instructions that help superintendents and landscape professions hook up a tank to the irrigation line and get started.
An internet search for tree-specific fertigation and irrigation-based pest control turned up much less though. It was not an exhaustive survey, but it looked like no commercially-available fertigation or chemigation systems are designed for trees in landscape settings.
This finding suggests that an opportunity may exist for companies already marketing fertigation to adapt existing systems. Or, some enterprising superintendent could use existing systems to target pests, or supply nutrients (to palms, etc?EUR??,,????'?????< In any event, university extension programs are a good place to start when looking for more basic information on fertilization rates and requirements. A sample of information is provided below. To learn more, visit the university?EUR??,,????'?????< Send comments and suggestions to LSMP editor Erik Skindrud at eskindrud@landscapearchitect.com.
In any event, university extension programs are a good place to start when looking for more basic information on fertilization rates and requirements. A sample of information is provided below. To learn more, visit the university?EUR??,,????'?????<
Send comments and suggestions to LSMP editor Erik Skindrud at eskindrud@landscapearchitect.com.
Palms have exacting needs when it comes to nutrients. Research has determined the best ratios of nutrients, however. These are available in palm-specific fertilizers.
Look on the label to make sure the nutrients are in the following proportions: nitrogen (10% to 20%), phosphorous (5% to 10%), potassium (10% to 20%), magnesium (2% to 5%), and (.5%) of manganese and iron.
The product should also contain sulfur and trace amounts of zinc and copper.
If palms are suffering from nutrient deficiencies, then supplemental amounts of the deficient nutrients will be required. Magnesium deficiencies are common on date palms (Phoenix species). Older leaves turn yellow first, progressing up to younger leaves. Leaflet tips yellow while the bases remain green. Correction of this deficiency requires the addition of magnesium sulfate to the soil.
Queen palms are often deficient in manganese, not to be confused with magnesium. Manganese deficiency on Queen palm causes the new leaves to become yellow or brown and frizzled, which gives this disorder its common name: “frizzle top.?EUR??,,????'?????< From John Begeman, College of Agriculture and Life Sciences, University of Arizona, ag.arizona.edu.
From John Begeman, College of Agriculture and Life Sciences, University of Arizona, ag.arizona.edu.
Raleigh, North Carolina
Francisco Uviña, University of New Mexico
Hardscape Oasis in Litchfield Park
Ash Nochian, Ph.D. Landscape Architect
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