FARMING NOTES

Bay of Plenty Beacon, Volume 1, Issue 66, 25 September 1939, Page 3

FARMING NOTES

tifie explanation if only one can dis cover it. and ihe success ol the P'*ac-

tice or pientinseeds from light ir.r.d on heavy land is no doubt partly due to the fact that such seed cnrVes less llnizoctonia. On light land there S less organic matter in the soil and therefore less fungoid growth. To avoid lo«s through misses, late plants,, and "all tops and no potatoes'" (1) Buy good clean seed, preferably ofT light land. (2) Sow in a warm soil. 00 Manure adequately i:i order to stimulate the plants ; n lh,,nrly stages. (!) Allow an interval of at least four years between successive crops.

COMBATING FUNGUS DISEASE THINGS TO WATCH Of all the crops of economic importance, the potato, moi e than other needs constant culling foi (iisca.se and foreign varieties if its cropping power and purity ar- to be maintained. When, roguing crops at flowering time or shortly altcrwaids it is not uncommon to come acioss plants that are obviously off type i and yet they show no true signs ct any of the virus diseases, such as leaf roll or mosaic. Quite a number of off types are caused by injury to the young plants during moulding, and often plants on the end of the rows look entirely different from it he rest of the ciop bccause they have been, trodden on by the horses manoeuvring to turn. I have heard such plants described as suffering from "swindle tree blight." Tn general nppcarance, the fdiage of the plant is more open than normal, and there arc often only one or two coarse haulms. The unper leaves curl and the flowering stalk is elongated. The plant has a harsh straggly nnpcarance, and stands out abo\e the rest of the.crop. COMPLAINT PREVALENT. These straggly tyncs have been pre valent throughout the crops, especi-1 allv during the last two seasons, and my own observations and reference to American and other authorities has confirmed my susoicions that injury by the fungus is the chief couse of this complaint. Few seed potatoes are entirely fiec from small black spots on the skin. These spots range in size from one* eighth or r,n inch to anything up to rj quarter of an inch, and they can be easily levered off with the fingenail.

Tliesp sno'ts. more correctlv termed a "black scurf," are the resting stage o-F the "fundus Rhizoctonia, known also as Corticium diving another stage or its life. T.u the H-clc scurf stage it is never a serious blemish, but when infected seM is planted the scurf develops into an active growth which will attack the young shoots near the growing points.

Low temperatures favour th~ fundus and in a late spring the shoots emerge and numbers are nipr>rd off before thev reach +he surface. The damaged shoot branches be'ow the inju v nnd the result is a Into nlant or, if the attack is severe, n complete miss in the row. Old setts dug up arc found to have numbers of ialf-growi*shoots roming from the eyes. EXTENT OF INJURY. Tniurv is not confined to the voting shoots, but under conditions favourable to the fungus healthy stems are attacked later nust ground level. Fine threads invrde the conducting vessels of the and interfere Avith the transportation not only of sap coming from the root-.; to the ]eaA r cs but also of sugars passing doAvn to the d'weloping tubers. The top lc3A T es show s'gns of AA'dting in hot Avcather. the condition being analogous to that caused by norscs tramping on end plants.

The sugars manufactured in the icavos cannot reach the young tubers in the soil, and the reaction of the plant is to form small potatoes around the stem at ground level; sometimes they arc found half-wav mi the stem in the axils of leaves. These tubers seldom develop to more than seed size, and are always very Some authorities describe this of the disease as "All lops find no potatoes," or "Little Potato." HOT A TIOX AL CRO P PIN G The old advice to growers who rogue certified crops, "WhcrM.n doubt dig it out" is good advice, but it is of litllc avail to rid the stock of those plants - is the lunr,us is carried

Oil ne-U']y I'll tubers and can also live I in the ground. Past experiments' have proved that with rotational cropping allowing a spell of at least four years between successive potato crops, the fungus will die out in ihe soil. The black scurf on the seed can bo killed by the use of disinfectants, such as formalin and corrosive sublimate. but the process is rather laborious for the average farmer and is ;;■> ,p;"' ! 1 )I■' <>n!y to small lots. Old custom'-; usually have. a s;-ien-(Coniinued foot previous column)