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Low Sugar Disease of sugar beet - PH0136

Description

A new disease of sugar beet appeared in 1991 in the Burgundy region of France. The disease was called 'Syndrome des Basses Richesse' or Low Sugar Disease because of its effect on the sugar content of the beet - a reduction to about 14-15% from an average of 17%. After an initial epidemic phase of two years the disease settled down to a low level of sporadic occurrence. The disease reappeared in France in 1997 with about 250 hectares of infected beet in the same region. The French sugar industry is worried about the likely effects of this disease on sugar production.

Research being carried out at INRA Dijon by Dr Boudon-Padieu has identified a stolbur phytoplasma vectored by a cicadellid, (leafhopper) tentatively identified as Pentastiridius beieri, as the probable causal agent for the French disease. High populations of this insect were observed in sugar beet plots in the summer. She has transmitted the phytoplasma into indicator hosts and sugar beet experimentally and is working on further characterisation of it as the disease agent. Dr Boudon-Padieu has in a recent publication noted that the presence of detectable phytoplasma DNA in the sugar beet samples analysed could not reliably be related to the expression of symptoms (1) (Gatineau et al, 2001)

In 1997 a similar disease was reported in beet crops in Norfolk but infection by phytoplasmas was never confirmed, possibly due to a lack of good diagnostic tests. Communications have been received that some Lavender crops in France may also be affected by phytoplasma. In 1999 sugar beet from SE Hungary with similar symptoms to the French disease were diagnosed as having phytoplasma of the aster yellows group, (first definitive record) by CSL (2) (Mumford et al, 2000). The French researchers have suggested that the beet phytoplasma they are investigating is a leafhopper-transmitted member of the stolbur group, (3) (Munchembled et al, 1999).

Phytoplasmas, (also known mycoplasma-like-organisms (MLOs) in older literature) are infectious organisms containing DNA that are confined to the phloem and xylem of plants. They are just visible using a light microscope. They resemble bacteria, are irregular in shape but have no rigid cell-walls. Phytoplasmas cause a large and varied group of diseases that affect crops, flowers and trees. Transmission of phytoplasmas is primarily by cicadellids (leafhoppers) and other sap-sucking insects.

Symptoms of Low Sugar Disease (LSD) include beet fields that may be completely yellow or that may develop a brown appearance in late summer. The sugar beet may have a pineapple-shaped crown, stunted growth and chlorotic and necrotic leaves and petioles. Leaves can also have small dots or angular spots with recent regrowth being small or deformed. The internal tap roots may show vascular browning.
Objective
1) To develop methods for the propagation of the phytoplasma from France.
2) To develop a methodology for the diagnosis of he phytoplasma involved in LSD.
Project Documents
• Final Report : Low Sugar Disease of sugar beet   (246k)
Time-Scale and Cost
From: 1999

To: 2001

Cost: £20,951
Contractor / Funded Organisations
Central Science Laboratory
Keywords
Plant health              
Plant Pests and Diseases              
Plants and Animals              
Fields of Study
Plant Health