LIBRO-CONGRESO-CITRUS

S15O11
Searching for citrus rootstocks resistant to Mal Secco disease: a review
Nigro F., Ippolito A., and Salerno M.G.
Department of Soil, Plant and Food Science, University of Bari Aldo Moro, Italy. antonio.ippolito@uniba.it
Mal Secco Disease (MSD) is a severe tracheomycotic disease of citrus caused by the mitosporic fungus Phoma
tracheiphila. Besides lemon, the most damaged species, MSD also affects other citrus species, such as cedar,
lime, bergamot, chinotto, sour orange, rough lemon, Volkamer lemon, etc. When the infection is through a
rootlet of a susceptible species, more frequently in the nursery but also in bearing plants in the grove, the
pathogen may remain segregated for many years in the inner layers of wood, leading to the particular form
of the disease known as ‘Mal Nero’; this syndrome is characterized by blackish discoloration of the hard
wood and by the absence of almost any external symptom. Eventually, after several years, the pathogen
reaches the sapwood, causing a sudden collapse of the canopy, also on resistant scions. Host resistance
remains the most desirable goal among the measures to control MSD, and the search for new and resistant
rootstocks, to replace the susceptible ones, has long been pursued by researches in Italy. This paper reviews
the conclusive data collected over almost three decades of researches, conducted both in the field and in
controlled environment, on the behaviour of putative lemon rootstocks towards MSD. The tested rootstocks
include: alemow, sour orange (S. Marina and undetermined selections), ‘Ichang’ lemon, ‘Yuzu’ orange,
‘Nansho Daidai’ sour orange, ‘Siamelo’, Citrange ‘Yuma’, citrumelos (‘Sacaton’, ‘Swingle 4475’, and ‘Swingle
FF9’), and the hybrids ‘Cleopatra’ x Poncirus, and Poncirus ‘Christian’ x ‘Cleopatra’.
S15P01
Endophytic actinomycetes for the biological control of Phyllosticta citricarpa
Glienke C. 1 , Savi D.C. 1 , Goulin E.H. 1 , Kava-Cordeiro V. 1 , and Silva Jr G.J. 2
1 Federal University of Parana (UFPR), Genetics, Brazil; and 2 Fundecitrus Fundo Paulista de Apoio a Citricultura (FUNDECITRUS),
Cientifico, Brazil. ch.glienke@gmail.com
The Citrus Black Spot (CBS) disease has caused innumerous losses in citrus producing regions in the world,
including Brazil, Australia and South Africa. This disease is caused by the fungus Phyllosticta citricarpa.
Actinomycetes are widely known due to its enormous capacity to produce secondary metabolites, the
pharmaceutical market by providing the most varied treatment options. Looking for biological control of P.
citricarpa, the present work aimed the isolation of endophytic actinomycetes of the medicinal plant Vochysia
divergens, and the bioprospecting of its secondary metabolites. The endophytes were tested against the fungus
P. citricarpa in vitro and in vivo using detached orange fruits. The endophytic isolate LGMB259 presented better
inhibitory activity in vitro and it was confronted with the fungus P. citricarpa in fruit tests. The metabolites of
other five isolates inhibited totally the emergence of the CBS disease symptoms in tests in vivo. To determine the
identity of these actinomycetes, the isolates were subjected to DNA sequence analysis of the rDNA 16S gene.
Ten isolates were classified as Microbispora sp. and two isolates were classified as Streptomyces sampsonii. The
other two isolates were identified as Micromonospora sp. and are apparently undescribed species. This is the
first report of the actinomycetes isolation from this medicinal plant, and the first report of actinomycetes with
activity against P. citricarpa. Financial Support: CNPq/MAPA, Fundecitrus, Fundação Araucária.
S15P02
Population genetics of Guignardia citricarpa in South Africa
Carstens E. 1 , Linde C.C. 2 , Slabber R. 3 , Langenhoven S. 4 , Schutte G.C. 5 , Fourie P.H. 1 , and McLeod A. 4
1 Stellenbosch University and Citrus Research International, Plant Pathology, South Africa; 2 Australian National University, Canberra
ACT, Research School of Biology, Ecology, Evolution and Genetics, Australia; 3 Stellenbosch University, Central Analytical Facilities,
South Africa; 4 Stellenbosch University, Plant Pathology, South Africa; and 5 Citrus Research International, South Africa. ec@cri.co.za
Citrus Black Spot (CBS), caused by Guignardia citricarpa, is an economically important pathogen of citrus in
South Africa (SA). The pathogen produces two types of spores, waterborne conidia on fruit, twigs and leaves on
the tree, and windborne ascospores from asci in leaf litter. In SA and Australia, epidemiological studies showed
XII INTERNATIONAL CITRUS CONGRESS 2012 - 259
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