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Cyprex 65 WP Controls Algae on Some GreenhoufT.
C:!iifr, ipnce p
A. R. Chase and L. S. Osborne :
University of Florida, IFAS
Central Florida Research and Education Center Apppka ji l-
CFREC-Apopka Research Report, RH-87-8
Algae can cause serious problems during the production' o f~Yilg
plants. They grow on pots, potting media, bench and walkway-surf~a-es,--
plastic, glass, and even on the plant leaves. Products such as sodium
hypochlorite (commercial bleach), copper compounds, and quaternary ammonium
compounds are available for algae control on nonliving surfaces such as
benches and walkways (2,4). Most of these products are not recommended for
use on plants since they can be toxic. Other research has identified
several fungicides which are effective in controlling algae growth on
capillary mats during crop production (3). Previous research by the
authors demonstrated that sodium hypochlorite (10% commercial bleach)
provided good short-term control of algae but regrowth occurred within 3
days. Dodine (Cyprex 65 WP), mancozeb (Dithane M45), and zineb (Dithane
Z78) provided the best control for 5 weeks following a single application.
The purpose of the research reported in this paper was to further
evaluate use of Cyprex 65 WP for algal control on surfaces such as
concrete, wood and capillary mats.
The efficacy of Cyprex in controlling algal growth on capillary mats
both before and after infestation with algae was tested in a series of
trials. Capillary mat pieces (2 x 2 inches) were used for all trials. The
mats were either allowed to become infested with algae prior to chemical
treatment or they were treated and then inoculated with algae. To
facilitate algal growth, mats were watered twice weekly with 5 ml of a 100
ppm Miller's 20-20-20. Chemical treatments were applied by dipping the mat
pieces into the appropriate solution for 5 seconds then placing on a wire
bench to drain for 10 minutes. Mats were then placed onto an inverted
petri dish lid and placed on a greenhouse bench where they were misted for
5 sec every 30 min (12 hours/day). Ratings on a scale from 1 (no algal
growth, white) to 5 (dense algal growth, dark green) were made periodically
up to 10 weeks following a single chemical treatment. Five pieces of mat
were used for each treatment in each test. The following rates of Cyprex
65 WP were tested: 3.8, 1.9, 0.9, 0.5, 0.4, 0.3, 0.2, 0.16, 0.12, 0.08, and
0.04 g/500 ml. In each test a water control was also included.
Rates as low as 0.5 g/500 ml Cyprex 65 WP were effective in
controlling algal growth on capillary mats for 10 weeks although the 0.9
g/500 ml rate was more effective over this period of time (Table 1). Lower
rates were very effective over a shorter period of time with 0.2 g/500 ml
being the lowest effective rate to give consistently good results for a 4
week period of time.
Associate Professor of Plant Pathology and Associate Professor of
Entomology, respectively, Central Florida Research and Education Center -
Apopka, 2807 Binion Rd., Apopka, FL 32703.
Treatment of transit benches with a long standing
made on 25 August with the following rates of Cyprex 65
15.0, and 30.1 g/500 ml. Very effective control of the
rates of 15 or 30.1 g/500 ml. The death and removal of
within 3 days of treatment.
algal buildup was
WP: 0, 3.8, 7.5,
algae occurred for
algae was apparent
Treatment of wood with relatively low rates of Cyprex 65 WP was not
effective when applied either before or after algal growth. The rates
tested ranged from 0.1 to 0.5 g/500 ml which were effective in controlling
the same algae on capillary mats.
Good control of algae on concrete blocks was achieved with rates of
Cyprex between 0.2 and 0.5 g/500 ml. Treatment lasted approximately one
month and was comparable to that seen for capillary mats at these rates.
Algal control on surfaces can be achieved with varying rates of Cyprex
65 WP depending both upon the surface treated and the interval between
applications. Capillary mats can be maintained relatively algae-free if
treated with rates of Cyprex equivalent to 0.2 g/500 ml applied every
month. Higher rates provide longer control on capillary mats and are
needed to provide good control on many other surfaces.
1. Chase, A. R. and L. S. Osborne. 1984. Controlling Algae in Foliage
Plant Production. Proc. Fla. State Hort. Soc. 97:274-278.
2. McCain, A. H. and R. H. Sciaroni. 1965. Alga control in the
greenhouse. Florists' Rev. 137(35-45):28, 79-81.
3. Powell, C. C. and K. J. Shumard. 1984. The chemical control of algae
on subirrigation mats in greenhouses. Ohio Florists' Assoc. Bul. No.
4. Vandiver, V. V., Jr. and T. R. Batterson. 1982. Algae-biology and
control. Fla. Coop. Ext. Serv. Weeds in the Sunshine, A-82-9, p. 1-23.
Table 1. Effect of Cyprex 65 WP on growth of algae on capillary mats.
Test Treatment Rating Rates per 500 ml water
Number date date 0 0.5 0.9 1.9 3.8
1 15 Sept. 26 Nov. 5a 2.4 1.3 1.2 1.1
2 7 Oct. 26 Nov. 5 2.4 1.2 1.2 1.0
Rates per 500 ml water
0 0.1 0.2 0.3 0.4 0.5
3 21 Oct. 26 Nov. 5 1.5 1.1 1.0 1.0 1.0
Rates per 500 ml water
0 0.04 0.08 0.12 0.16 0.20
4 18 Nov. 15 Dec. 5 3.7 2.9 2.8 2.5 1.7
aAlgal growth was rated from
growth, dark green mat).
1 (no growth, white mat) to 5 (dense