Abstract
Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc), is a bacterial disease of citrus and results in peel blemishes rendering fresh fruit unsalable. Xcc is most active in warm, wet Florida summers where tissues are infected during periods of active growth. Melanose, caused by Diaporthe citri, is common in citrus producing countries, but, like canker, is only important for fresh market fruit. To control canker and melanose, Florida growers spray trees with copper formulations (Cu), but these sprays are removed by strong rains and intense radiation of Florida summers. A study was undertaken in FL commercial grapefruit groves in 2009 and 2010 to assess the efficiency of a spray combining copper with a specially formulated, hydrating wax (WashGard?) (WG). Using a 21-day spray schedule for the season, fruit were sprayed with WG + Cu, Cu and Control (no spray). Fruit from trees sprayed with WG + Cu had approximately 10 and17% more canker free fruit in 2009 and 2010 respectively compared to trees sprayed with copper alone. Compared to control trees the canker free fruit incidence was increased by ≈10% in 2009 and 57% in 2010. For melanose there was 40% more disease free fruit (treated) over fruit from trees with no treatment in 2009 and approximately 20% more in 2010. Controlling infection with this spray significantly reduces citrus canker and melanose, increasing the percentage of marketable fruit.
Highlights
Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc) is found on all citrus cultivars, with grapefruit, Mexican lime and lemon being the most sensitive [1,2,3,4] (Figure 1(a))
Results for both 2009 and 2010 were determined using disease assessment keys, a standard method for assessing disease in the field and on field commodities [26,27,28]. For both years and in all grove areas data show that trees sprayed with WG + copper formulations (Cu) had significantly more unblemished fruit than both the untreated controls and trees sprayed with copper alone
For 2009 in grove A, fruit treated with WG + Cu had almost 10% more blemish free fruit than those treated with the copper alone (P < 0.003) or untreated controls (P < 0.001) (Figure 2)
Summary
Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc) is found on all citrus cultivars, with grapefruit, Mexican lime and lemon being the most sensitive [1,2,3,4] (Figure 1(a)). Citrus canker, caused by Xanthomonas citri subsp. Citri (Xcc) is found on all citrus cultivars, with grapefruit, Mexican lime and lemon being the most sensitive [1,2,3,4] (Figure 1(a)). Wet, weather the bacteria ooze from the lesions and are carried in wind driven rain to susceptible tissue. One of the strongest impacts of canker is that it causes severe restrictions on fruit movement to some markets [4]. Non (Sacc.) Traverso & Spessa) is a fungal disease of citrus that causes a superficial blemish on the peel reducing acceptability in the fresh market [5] (Figure 1(b)). All citrus varieties grown in Florida are susceptible but as in canker, grapefruit are the most sensitive [5,6,7]. In humid and wet weather, conidia exude from pycnidia in dead wood and are washed down the tree from the canopy [5,6,8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
