196 
The N.Z. Journal of Science and Technology, [Nov. 
the flax industry lies partly in increasing the areas by planting. For this 
purpose much poorer ground than that used at present would suffice. 
9. Summary and General Conclusions, 
(1.) This report gives an account of the behaviour of certain marked 
flax-plants in the Ashlea and Miranui flax areas during a period of fourteen 
months. This behaviour is considered a reliable index of the progress 
of events so far as the yellow-leaf is concerned in the above areas for the 
period stated. 
(2.) Although some idea of the progress of the disease may be gained 
from the observations mentioned in (1), yet too much reliance must not 
be placed upon them as an indication of what may happen in the future. 
(3.) My former opinion that yellow-leaf is not an infectious disease is 
reversed, and the opinion is advanced that it is an infectious disease 
probably due to fungoid or bacterial attack. 
(4.) My former statement that yellow-leaf is favoured by stagnant 
water is upheld, together with the obvious conclusion that the disease would 
not be nearly so bad were the swamps better drained in winter and kept 
wetter in summer. 
(5.) The conclusions of (4) are supported by the distribution of yellow- 
leaf in the Manawatu, at Waikanae, and near Plimmerton, in the North 
Island, and throughout the South Island generally, this latter knowledge 
the outcome of seeing the plant under all the conditions it can tolerate. 
(6.) Periodical examination of the marked plants has shown—(a) That a 
great improvement is taking place at the present time ; ( b) that there is 
an improvement in autumn and winter, which is followed by deterioration 
in spring and summer, at which latter season the flax is at its worst ; 
( c ) that a large percentage of healthy plants can remain healthy even when 
in close proximity to diseased plants ; (d) that a flax-bush itself can be in 
perfect health in one part and dying out in another part, and that such a 
bush may eventually make most excellent flax ; ( e ) that when a portion of 
a diseased plant which by extension of the rootstock has gained a piece 
of level ground it almost always becomes remarkably healthy and rapidly 
makes good flax ; (/) that diseased plants frequently recover and may 
become quite as good as plants which have never been affected ; ( g ) that 
great fluctuations may occur during the year, recovery being followed by 
disease, this again by recovery, and vice versa ; (h) that even during the 
worst period of the disease more originally healthy plants remained healthy 
than became diseased ; ( i) that a large percentage of healthy plants remained 
healthy all the time ; (j) that a considerable percentage of diseased plants 
not merely recovered but became equal to the best unaffected plants ; 
(k) that very few plants die outright; (l) that a small amount of disease may 
be beneficial, since the removal of a few leaves leads to better development 
of the remainder ; (m) that the plants of an area cut when badly diseased 
may remain virtually free from true yellow-leaf symptoms for over a year 
and eventually grow vigorously ; (n) that even if a general recovery has 
set in it is most likely that for some years there will be seasonal fluctua¬ 
tions ; (o) that there are probably plants not liable to the disease, and 
that from some of the marked plants material is to hand for the selection 
of a race which cannot take the disease ; (p) that under certain circum¬ 
stances it would be a fair business proposition for the Flax-millers’ Associa¬ 
tion to spend money on raising such a race as mentioned in (o), since it is 
probable that it may be profitable to extend the flax areas by planting. 
