RSD Survey Data - 2004

Samples Tested by CIRAD, Guadeloupe, using Tissue (stalk) Blot Technique

Estate/Farm	Variety	No. Stalks Sampled	No. Stalks Positive	Infected Vascular Bundles/20
St Thomas Sugar	BJ7465	6	0
	B51129	6	0
	D14146	6	6	10
	BJ7314	6	0
	BJ7465	6	0
Long Pond	BJ7452	6	0
	BJ78100	6	0
	BJ7015	6	0
	BJ82119	6	0
	BJ7548	6	0
Frome	BJ7465	6	0
	BJ82156	6	0
	BJ82119	6	0
	BJ7355	6	0
	BJ7504	6	2	20
	BJ82119	6	0
	BJ7015	6	0
	BJ7938	6	0
	BJ8252	6	0
	BJ7504	6	0
New Yarmouth	BJ8859	6	0
	BJ82102	6	0
	BJ8252	6	0
	BJ8252	6	0
	BJ8226	6	0
	BJ7015	6	0
	BJ7627	6	0
	BJ8252	6	0
	BJ7504	6	0
SIRI	BJ8783	6	0
	BJ8859	6	0
	BJ8534	6	0
	BJ8708	6	0
Bernard Lodge	CR67400	6	0
	BJ78100	6	0
	BJ7555	6	0
	BJ7504	6	0
	BJ8226	6	0
Monymusk	BJ7015	6	0
	BJ7504	6	0
	BJ82119	6	0
	BJ8252	6	0
	BJ7627	6	0
Worthy Park	BJ7262	6	5	12
	BJ7627	6	0
	BJ7452	6	0
	BJ7938	6	0
	BJ7452	6	1	3
	BJ7262	6	4	11
	BJ7504	6	0
	BJ82119	6	1	13
	BJ7627	6	3	9
	BJ82156	6	1	13
Appleton	BJ7504	6	2	20
	BJ7262	6	1	5
	BJ7504	6	0
	BJ7465	6	0
	BJ7015	6	0
	BJ8226	6	0
	BJ7452	6	0
	BJ7015	6	0
	BJ7504	6	0
	BJ7015	6	0
Total		378	26
			6.88%

Comments

This survey was done in collaboration with CIRAD, Guadeloupe, using a recently developed technique called the tissue blot. A freshly taken core from the base of each stalk was pressed against a specially developed membrane, which was then packaged and sent to Guadeloupe for analysis. The technique is considered fairly reliable (though fairly expensive) but the pathologist recommends that results be confirmed by using one of the older methods. Plans are being made to do this at Montpellier, France.

From each field tested, 6 tissue blots were made (from 6 stalks). A score of zero means none of those 6 stalks showed evidence of the pathogen. Although 6 stalks would seem a small number, pathologists claim that RSD is of such a nature that this adequately determines the likelihood of the pathogen being present at any significant level in a field. So a long sequence of zeros as shown in the table would indicate a relatively low level of infection – in fact just 6.88% of all stalks tested. The greater the number of stalks that are positive is an indication of greater distribution within a field. Thus D14146 at St Thomas Sugar had all 6 stalks infected. In this survey, Worthy Park shows the highest number of fields with positive readings. Ironically, Worthy Park is having its best crop in years, averaging 93 tc/ha up to mid-February, which indicates that where good agronomic practices are maintained, the RSD effect might hardly be measurable.

01/03/04

SIRI

Kendal Road, Mandeville