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Windbreaks for Citrus Canker Control Silk Oak (Grevillea robusta) a Choice for Producers October 2006


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Fact Sheet
Windbreaks for Citrus Canker Control

Silk Oak (Grevillea robusta) a Choice for Producers
October 2006



Overview
Citrus canker, caused by the bacterium Xanthomonas axonopodis pv. citri, is a leaf, fruit, and stem spotting disease that affects numerous species, cultivars, and hybrids of citrus and citrus relatives.

Citrus producers in Florida are being advised to use a combination of resistant varieties, chemical sprays, and windbreaks to manage the impact of the disease.


Why Windbreaks?


T
To assist Florida citrus producers, the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS) in Florida now includes the planting of windbreaks for citrus canker control as a conservation practice eligible for cost share payments under the Environmental Quality Incentives Program (EQIP).

Silk oak trees (back) planted in wind -break in Brazil for citrus canker control.
he vast majority of the infection occurs by wind-blown rains. Winds of 18-20 mph are needed to actually force bacteria into the stomates on leaves and fruit. Work in Argentina has found that the number of canker lesions was ten times greater on the side of the tree exposed to the prevailing winds than on the protected side of the same tree. In tests in nursery situations, artificial windbreaks greatly diminished the distance of spread of canker down the nursery row and reduced disease to only a few scattered lesions. For this reason, the citrus canker research community in Florida believes that windbreaks are the most critical component for management of the disease.

Plants for Windbreaks

Trees and shrubs used in windbreak plantings for citrus canker control need to be easy establish, fast growing, low maintenance, etc. A list of the plant species recommended for windbreak planting can be found on the back of this fact sheet.



Silk oak (Grevillea robusta) is new to this list. Like eucalyptus, this is a non-native, fast-growing species that is best suited for coastal flatwoods. This species is used extensively in Brazil and less so in other parts of the world where citrus is grown. This evergreen tree is suited to most soils except very calcareous or chronically wet conditions. It can be used by itself in single rows. BUT, it is susceptible to mushroom root rot if grown in wet sites and the trees become brittle as they age. Branch loss can be expected from wind damage. Also, the species is not very cold hardy. Thus, until further experience is gained in Florida, Grevillea is only recommended for the warmer, coastal areas of the citrus industry.

How to Apply for Assistance

More windbreak cost share information will be available soon from your local NRCS office or http://www.fl.nrcs.usda.gov/programs/eqip/flequip.



The FY2007 sign up period in Florida ends on December 15, 2006.
For additional information contact your local USDA-NRCS Service Center office at http://offices.sc.egov.usda.gov/locator/app or Jeffrey Woods, Assistant State Conservationist for Programs, Jeffrey.Woods@fl.usda.gov, 352-338-9515.

1More information on these plants can be found at http://www.crec.ifas.ufl.edu/extension/windbreaks/species.htm.



Plant species for Citrus WindbrealsGroves1.


Common name


Scientific name

For use in citrus production area


Height at 2 yr


Mature height


In row spacing

Trees and other

Slash pine

Pinus elliottii

Flatwoods

8-10 ft

80 ft

3-6 ft

Sand pine

Pinus clausa

Ridge

6 ft

70 ft

3-6 ft

Eucalyptus

Eucalyptus grandis

Soils not suited for pine and ridge soils with irrigation

15-20 ft

90 ft

3-6 ft

Silk oak

Grevillea robusta

Coastal flatwoods

10 ft

40 ft

6 ft

Red cedar

Juniperus viginiana or J. silicola

Ridge and flatwoods

6 ft

40 ft

4-6 ft

Bamboo

Bambusa spp. (non running species only)

Ridge and flatwoods

20-30 ft

40-60 ft

4-6 ft

Shrubs

Walter’s viburnum

Viburnum obovatum

Ridge and flatwoods

6-10 ft

20 ft

6 ft

Sweet viburnum

Viburnum odoratissimum

Ridge and flatwoods

6-10 ft

20 ft

6 ft

Saw palmetto

Serenoa repens

Ridge and flatwoods

4 ft

6 ft

3 ft

Crape myrtle

Lagerstroemia indica

Flatwoods

10 ft

30 ft

3-6 ft

Wax myrtle

Myrica cerifera

Ridge and flatwoods

6-10 ft

10-15 ft

6 ft

Simpson’s stopper

Myrcianthes fragrans

Ridge and flatwoods

6 ft

20-30 ft

3-5 ft


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