16 
the soil to the full with the particular organisms, both animal 
and vegetable, concerned in their decay, and hence if cracking 
occurs the parsnip might be expected to be rapidly destroyed. 
Lastly, liming has been neglected. Experiments carried out b 
Messrs. Yates in 1917 show a decided improvement where lime 
was applied. 
Yet another cause of the severity of the canker attack may lhe 
in the nature of the variety of parsnip grown. As already men- 
tioned breeders aim at a small core and ample flesh, an ideal 
well seen in the Evesham parsnip root, which is noted for its 
bulky fleshy top. Such a soft mass of parenchymatous tissue 
would probably be easily stimulated to extensive growth after 
rainy periods during the summer months and to rapid expanston 
of the inner tissues. The breeders may have exceeded the limits 
in that direction and produced a parsnip particularly subject to 
a physiological defect. As evidence in favour of this view 1t may 
be mentioned that in allotments in Worcester, though the 
long slender parsnip such as ‘‘Student’’ showed rupturing of 
the rind and a certain amount of canker, these were not so 
‘extensive as in the Evesham parsnip. 
Preventive Treatment.—In order to reduce the amount of 
surface-cracking and canker the following treatment, based on 
the above conclusions, may be recommended : — 
1. Too rich a soil must be avoided. 
2. Late sowing should be adopted. Such observations as it 
has been possible to make in 1917 tend to confirm 
growers’ statements that plants sown in the end of 
April or beginning of May suffer much less than those 
sown in February. 
3. Liming must not be neglected. As well as improving the 
tilth, lime acts by liberating reserves of nitrogen and 
potash, and its effect on the parsnip is seen in the im- 
proved quality of the crop both in size of roots and 
decrease in the amount of decay. 
4. A dressing of salt has been found very effective by some — 
growers. On heavy soils 5 cwt. per acre should be 
applied, and on light soils up to 10 ewt. per acre may 
be used. The salt may act by liberating a certain 
amount of potash from the soil, and one of the most 
marked effects of potash is to retard maturation and to 
enable the plant to continue its vegetative growth. It 
is possible that this effect may extend to the phellogen 
(rind-producing layer) and consequently render it less 
liable to rupture. For the same reason potash manures 
should prove beneficial. . 
5. A proper rotation should be given, and parsnips must 
rors be grown for two years in succession on the same 
Summary.—The canker of parsni 
: p or the decay of the upper 
part of the root during late summer and aiken is a diease 
