11 Feb., 1918.] Nursery Stock. HI 



NURSERY STOCK. 



As citrus culture has during the past few years received attention 

 from growers in the irrigated areas of the northern part of the State 

 and is capable of considerable extension without the risk of over-pro- 

 duction it is necessary for growers to understand the nature and limita- 

 tions of the stocks used for the foundations of their trees. With but 

 few exceptions Australian nurserymen have exclusively Ubed the wild 

 lemon as a stock, while citrus growers in other countries, suc'n as Cali- 

 lornia, Florida, Algeria, as well as European gix)wers, give preference 

 generally to the sour orange as a stock. Seedlings from the sweet 

 orange, Otaheite, Tritoliata, and Pomelo have also been tried, but have 

 not come into favour, with the exception of the first mentioned, owing 

 to their limitations or unsuitability. 



In the selection of citrus trees the adaptation of the stock to soils 

 and climatic changes, and the reciprocal influence between stock and 

 scion should not be overlooked. It cannot be denied that such an 

 influence is exerted m the direction of hardiness, rate of growth, shape 

 of the tree-head, as v/ell as the quality of the fruit produced. 



Sour Orange Stock. 



In poin!: of hardiness the sour orange (Citrus vulgaris) is considered 

 to be much superior to the wild lemon (Citrus livionuni). At the Wah- 

 gunyah nursery last winter, when the temperature fell below 22 deg. 

 Fall., no appreciable damage was done to the one-year-old bed of sour 

 change stock, while the lemon stocks were frosted back to the crown. 

 1 ne sour orange stock has an abundant root system, which penetrates 

 well into the soil. In this respect it has a considerable advantage 

 0V6 if many other stocks as the roots are not subjected to the same varia- 

 tions of temperature as those of a more shallow rooting habit, nor are 

 they so liable to suffer injury from the plough during cultivation. In 

 this deep rooting habit the trees have a larger area from which to 

 derive the plant food of the soil as well as their roots being in contact 

 with a more or less permanent water supply. 



Collar-rot (mal-di-gomd) is one of the most serious troubles of the 

 orange grove, as, working insiduously on the trunk beneath the surface, 

 the disease involves the ruin of the tree before the grower is aware 

 of its presence, and too late for any remedial measures being taken, 

 iriy the death of numerous trees here and there throughout the grove, 

 the grower in a few years finds the orchard unprofitable, but by the 

 use of the sour orange stock this condition can be avoided as the sour 

 orange is not subject to this particular disease. 



Trees worked on the sour orange require not only plenty of moisture 

 but also rich soils in humus. On the poorer and drier class of soils they 

 do not grow so large as those worked on the wild lemon. In general, 

 the sour orange stock is most suitable for our irrigation areas, where 

 plenty of moisture can be supplied, and the fertility of the soil main- 

 tained. From the first time of cropping the fruit borne by trees 

 worked on the sour orange is of good quality, being thin-skinned, juicy, 

 and showing little '"' rag." They are somewhat shy in bearing at first, 

 but with age they fruit well, and the trees under suitable conditions are 

 Icng lived. 



