Agriculture Reference
In-Depth Information
Table 19.2
Some symptoms of diseases and physiological
disorders
Many examples of variegations are genetically
chimaeras that may revert, by producing shoots and
leaves with the original green leaf colour.
Pruning out the green shoots that appear may require
constant attention and patience.
Symptom
Cause
Other cause
Leaf spot
Fungus, e.g. apple
scab
Bacterial canker
(Prunus)
Raised leaf spots
Rusts
Oedema (croky spots)
White covering on
leaf
Powdery
mildew - upper
Spraying hard water
Symptoms of disease and plant
disorders
Table 19.2 presents a summary of the most important
symptoms to help the reader 'home-in' on disease
problems and physiological disorders.
Downy
mildew - lower
Leaf yellowing
Low nitrogen levels
Root disease
Brown edge to the
leaf
Low potassium
Leaves curl and go
brown
Underwatering
Further reading
British Crop Protection Council (2014)
UK Pesticide
Guide
. BCPC.
Brown, L.V. (2008)
Applied Principles of Horticulture
.
3rd edn. Butterworth Heinemann.
Buczacki, S. and Harris, K. (2005)
Pests, Diseases and
Disorders of Garden Plants.
Collins.
Costello, L.R. (2003)
Abiotic Disorders of Landscape
Plants
.
University of California, Agriculture and
Natural Resources
.
Greenwood, P. and Halstead, A. (2009)
Pests and
Diseases
. Dorling Kindersley.
Hessayon, D.G. (2009)
Pest and Weed Expert
.
Transworld Publishers.
RHS (2013) Fungicides for home gardeners. Online:
www.rhs.org.uk/media/pdfs/advice/fungicides. RHS
Advisory Service.
Dry, crumbling
leaves
Plants overheated
Too much fertilizer
Yellow leaf veins
Low magnesium/
iron
Dark coloured leaves
Low phosphorus
Lower leaves yellow
Wilt fungus
Overwatering
Yellow/green leaf
mottle
Virus mosaic
Mutation/chimaera
Fruit spots
Fungus
Bitter pit (apple)
Sunken fruit lesions
Blossom end rot
(tomatoes)
Bud or leaf drop
Sudden change of
temperature
Stems elongated
Too little light
Whole plant wilts
Severe
underwatering
Wilt disease, vine
weevil grubs
Fluffy mould
Botrytis (grey)
Penicillium (blue)
Brown stem lesions
Tomato mosaic
virus
Swollen woody
stems
Fungal/bacterial
canker
Oozing from woody
stems
Bacterial canker/
fireblight
Brown roots
Root rot
Overfertilizing
19
their interesting leaf appearance, especially leaf
variegation (see p. 90). Common examples of these
are
Euonymus fortunei
'Emerald and Gold' (see
Figure 19.32) and Norway maple (
Acer platanoide
s
'Drummondii'). Variegation is also seen in varieties and
cultivars of species such as
Hedera
,
Cornus
,
Daphne
,
Ilex
and
Eleagnus.
Please visit the companion website for further information:
www.routledge.com/cw/adams
