(\\kXE — Brown Rot of Citrus. 
2i 
liifs type cultures, and stated that besides differiji^’ from Pytidacystis^ 
“it dilTered markedly culturally from Plintophthora eactonun^ P. 
in.festans, P. enjthroscptica, P. fapi and P. paralitica.'' Tne 
■writer has' also been a.ble to compare it with cultures of Ppihiavijstis 
ci t rophthora and Phutophlhora t crrcst ris recei ved from Profess; o' 
Fa-wcett, of t-lie Pitriis Kxperiment Station. Xbiiversity of ralifornia, 
and with cultures of Pi/thiacifstis' tcrrcstris received from :^[r. Water- 
house and has found it to be readily distinf>‘uishable. 
After the discovery of tlie iiatho^en in U)2o. and after tin 
difliculties of isolation had beeJi overcome the seo'^on for the diseas(> 
closed. It was fouml however, that the organism developed on 
affected twigs and leaves in water, l)ut rarely, if ever, on affected 
fruits under the same conditions; tliat spores were develo))ed in 
nature on all affected parts of citrus trees during t)v immediate!'' 
foMowiug wet weather in the winter; tliat sjiores in Avater germin 
ated either as zoosporangia or couidia. Few attempts at infectiou 
were made. Successful infection of oranges liy spores was secuia'd 
in one case. 
The patho''’eu was definitely dedmunined from oranges, mandariiu^ 
and lemons grown at various jiarts of the hill a.nd coastal iihiin 
areas. At Harvev a case was noted where lemon seedlings growji 
for stocks Aver(' more or less defoliated, and man.v kilh'd. 
Iduring the summer of P)23-P)24 the cultures died. 
On 19th June, 1924, diseased fruits were obtaiiu'd from Hicklov. 
and the organism again isolated. The first winter rains had com- 
menced in the early part of l\lay. one inch being recorded on lOth- 
]2th. The disease Avas in evidence until the end of Octoiier, and 
AAas again found on all A'arieties of citrus, both on leaves and fruit 
and in all com nercial citrus areas. Isolations AA'ere made from oi'ange 
and mandarin leaves and fruit, the iiathogen being identical Avbli 
that found the ])re\’ioiis year. ^ oung orange trees Avere infected 
by spore suspensions in Avater and the iiathogen recovered from typi- 
cally affected leaA’es. 
Ilunng the summer of 1924-2d tin' cultures Avtwe maintainc'd 
alive by storing in closed Mason jars in a cool safe (Ooolg'ar<be 
safe) with hessian sides kept Avet by a constant supply of Avater 
and placed in a draught. The organism Avas found to be very sus 
ce]>tible to heat and to drying out. Sub-cultures could be made to 
groAv during tlu' summer only at the reduced temperatures of tlie 
cool safe Avhich rarely exceeded 6oc>F. 
On 29th May, 192.). the disease Avas again found at Maddington 
near Perth on orange leaA'es and fruit. The first Avinter rains had 
commenced on 19th and 20th May with a fall of 1.83 inches at 
Perth. 
