Anthracnose of Sansevieria trifasciata caused by Colletotrichum sansevieriae

During August 2010, several nurseries located throughout South Florida submitted Sansevieria trifasciata samples to the Florida Extension Plant Diagnostic Clinic in Homestead FL.  The leaves had round water soaked lesions and as the disease progressed, lesions rapidly enlarged and coalesced resulting in severe leaf blight (Figures 1 & 2). Both young and mature leaves were affected (Figure 2 & 3).

Closer examination of mature lesions indicated the presence of numerous brownish black acervuli that were characteristic of Colletotrichum species (Figure 4). Further morphological, cultural, and molecular studies resulted in identification of the causal agent as Colletotrichum sansevieriae.  Based on the severity of the disease for commercial Sansevieria producers a series of fungicide efficacy trials resulted.

Evaluate and compare the efficacy of preventative and curative fungicides for managing anthracnose

Host: Sansevieria trifasciata ‘Laurentii’
Pathogen: Colletotrichum sansevieriae

Plants were grown in 3-gallon containers containing Faford potting soil amended with Florikan 18-6-8 slow release fertilizer.  Experimental units were a plant treated with a single fungicide treatment, with 6 repetitions in a randomized complete block design with sub-sampling.  Fungicides were mixed in a 1-gallon total volume, and applied as a foliar spray until runoff (approx.16 fl oz per plant).  Four applications were made for each treatment.  The first treatment was applied on 12/8/11 and the final application on 1/26/11 for a total of 4 applications for each treatment.  On 1/5/11 plants were inoculated with a spore suspension of 1x105 spores/ml. Inoculum was sprayed on plant foliage until runoff.  Note exception for Xeroton X3 in the curative trial.


Disease pressure throughout the duration of the trial was moderate to severe.  Preventative applications of Pageant significantly reduced disease incidence and severity resulting in 100% marketable plants.  Preventative applications of Heritage, Concert, and Torque all significantly reduced the number of lesions and disease severity resulting in 83% marketable plants.  Results indicate that a preventative spray program is necessary to control this disease. To minimize the risk of resistance in the pathogen population all fungicides should be rotated according to the manufacturer’s label.  Note Fungicide Resistance Action Committee (FRAC) codes are Disarm (11), Pageant (11), Heritage (11), Concert (3), Affirm (19), and Torque (3). UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition

Treatments:
1. Non-inoculated control
2. Inoculated control
3. Disarm 480 SC (fluoxastrobin) @ 16 ounces/100 gallons; 14 day
4. Pageant (pyraclostrobin + boscalid) @ 18 ounces/100 gallons; 14 day
5. Heritage (azoxystrobin) @ 6 ounces/100 gallons; 14 day
6. Concert (propiconazole + chlorothalonil) @ 28.5 ounces/100 gallons; 14 day
7. Affirm WDG (polyoxin D zinc salt) @ 0.375 lbs/100 gallons; 7 day
8. Torque (tebuconazole) @ 7 ounces/100 gallons; 14 day
9. Xeroton X3 (hydrogen peroxide + acids) @ a 1:1500 dilution; 7 day spray interval

Preventative Spray Program

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Curative Spray Program

Xeroton X3 @ a 1:500 dilution each day for the first 3 days then @ a 1:1500 dilution on a 7 day schedule.

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