Late Winter Citrus Management Considerations

Late Winter Citrus Management Considerations

Both niche market farmers and home gardeners may be uncertain about late winter management of Satsuma trees.  Several questions that have come in to the Extension Office recently include: Should I prune my trees? Why are the leaves yellow? How soon should I fertilize?  The focus of this article is to provide some answers to these common questions.

Should I prune my tree?

Jackson County citrus grove with branches allowed to near ground level. Image Credit Jose Perez, UF / IFAS

This is a complicated question that is best answered with “it depends…”  Pruning is not necessary for citrus, as it is in many temperate fruits, to have excellent production quality and quantity. Citrus trees perform excellently with minimal pruning. The only pruning necessary for most citrus is removing crossing or rubbing branches while shaping young trees, removing dead wood, and pruning out suckers from the root-stock. Homeowners may choose to prune citrus trees to keep them small, but this will reduce potential yield in a commercial setting, since bigger trees produce more fruit.

Often, maturing Satsuma trees produce long vertical branches. It is tempting to prune these off, since they make the tree look unbalanced. To maximize yield, commercial Satsuma growers allow these branches to weep with the heavy load of fruit until they touch the ground. This allows increased surface area for the tree, since the low areas around the trunk are not bare. Additionally, weeds are suppressed since the low branches shade out weed growth. The ground under the trees remains bare, thus allowing heat from the soil to radiate up during cold weather events. The extra branches around the trunk offer added protection to the bud union as well. If smaller trees are desired for ease of harvest, ‘flying dragon’ root-stock offers dwarfing benefits, so that the mature scion cultivar size will only grow to 8-10 feet tall.

Why are the leaves yellow?

Leaf deficiency with heavy fruit load. Image credit Matthew Orwat, UF / IFAS Extension

Heavy fruit loads were produced in many groves throughout Northwest Florida last year. When fruiting is heavy, citrus trees translocate nitrogen and other nutrients from older leaves to newer growth and fruit. Therefore, temporary yellowing may occur and last until trees resume growing in the spring. Remember, never fertilize after early September, since fertilizing this late in the year  can reduce fruit quality and increase potential for cold injury. If a deficiency, as in the photo above persists through spring, consider a soil test, or consult a citrus production publication to determine if additional fertilizer should be added to your fertilizer program.

How soon should you fertilize?

Although most Florida citrus publications recommend fertilizing citrus in February, they don’t take into account the potential for late frost in the Panhandle. Thus it makes more sense to wait until mid-March for the first fertilizer application in this region. Citrus trees don’t require a fertilizer with a high percentage of nitrogen, so it is best for fruit quality if an analysis of around 8-8-8 with micro-nutrients is used. Fertilizer should be applied in the drip-line of the tree, not around the trunk. The drip-line of a mature tree is generally considered to extend one foot from the trunk out to one foot from the edge of the furthest branch tip from the trunk. For fertilizer quantity recommendation see the chart below.

Through awareness of the unique managements techniques inherent to Panhandle citrus production, increased yields, better quality and healthier trees can be achieved.

 

For more information on this topic please use the following link to the UF/IFAS Publication:

Citrus Culture in the Home Landscape

 

Soil Test First!

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Matthew Orwat, Horticulture Agent I, Washington County Extension

Last week’s warm spring-like weather has reminded producers that it is time to prepare this year’s fertility  management plan. This reminder is timely because there is still time to prepare for the growing season ahead. Before producers add fertilize or lime, however, it is vital to understand the condition of the soil.

One of the easiest methods to assess the condition of a production area’s soil is to obtain a soil test. Soil tests effectively determine the pH and nutrient levels of the soil in a given area.  It is essential that the test be collected correctly so that it accurately reflects the nutrient levels in the production area.  All that is needed to take an accurate soil sample is shovel or soil probe, and a plastic bucket. Metal buckets will contaminate soil sample results, so a plastic bucket is an absolute requirement.  To collect your soil sample, follow these guidelines:

  1. Identify the production area(s) to be sampled. Use one soil sample bag for each area.  Uncharacteristic or problem areas (such as depressions, etc.) within the production area should be sampled separately. 
  2. Using a shovel (or soil probe), remove soil from a number of locations within the production area. The more soil collected from the sample area, the more accurate the results will be.  Soil should be removed from the top 6 inches.
  3. Discard any plant material (such as leaves or roots) and deposit the soil into the plastic bucket. When you are done collecting soil, mix all the soil in the bucket to ensure it is well blended.  You will have much more soil than you need to fill the sample bag, but a well-mixed representative sample is important for good results.
  4. Spread the soil from the bucket onto newspaper and allow it to dry thoroughly. This may take up to 24 hours.  A dry sample is very important because moisture may affect the results.
  5. Once dry, pack approximately 1 pint of soil into the soil sample bag (filled to the dotted line) These bags are available free from your county Extension office..  

The best soil test value is the $7.00 soil test which includes analysis of phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in addition to soil pH and liming requirement. The proper form should be filled out and mailed to the University of Florida with the soil sample and payment.  Results will usually be sent back within 1-2 weeks.   Click here to view a sample soil test report.

The soil sample report will include lime and fertilizer requirements. Remember that the recommended fertilization rates in the report are in pounds of nutrient, not pounds of fertilizer. For example, if it is recommended that the producer apply 50 pounds of nitrogen per acre and their fertilizer analysis is 10-10-10, they would need to apply 500 pounds of fertilizer. This is because 10-10-10 fertilizer contains 10% nitrogen.

For more information, consult your local county extension office, visit the UF/IFAS Extension Soil Testing Laboratory website, or the UF/IFAS publication Standardized Fertilization Recommendations for Agronomic Crops.