ORCHARD PESTS.

Otago Witness, Issue 2622, 15 June 1904, Page 10

ORCHARD PESTS.

GOVERNMENT FOMOLOGIST'S ADVICE.

It has been thought advisable, in oonse- ■ quenee of the provisions of the Orchard j and Garden Pests Ac* coming into force, ! to ask Mr Blackmore, fhe Government Pomoj logist, to supply this paper with informa- *■ tion upon the essential details underlying i the principles of spraying and the control of orchard pests, and thus enable growers of fruit to think and act for themselves -in putting thes© fundamentals into sucessful practice. Spraying (said Mr Blackmore) is a necessary, though fairly expensive operation ; it is, at the same time, the one most easily slighted, for it is the most exacting throughout the whole process of fruit-growing. Good appliances, pure materials, and, above all, patient and intelligent attention to every detail, in both mixing and application, are prime requisites for success. In fact, the importance of doinig the work just at the proper time, and with the right materials, cannot be, too strongly emphasised. In regard to the nature of noxious orchard pests, or plant maladies, the pomologist remarked, they consist of three elapses. 1. Undetermined affections, such as the "silver Might" of the plum. 2, Fungous disease, such »s peach ourl and apple -scalx- - 3. Insect enemies, such as apple scale and -eodlin moth. Much" time has been given by investiiga.tors to th© study of 'means, and methods of fighting these injurious insects and plant diseases, and various sprays, or dust mixture, are used against them. Those materials which are used tc- destroy insects are termed "insecticide.3" ; those used against the fungi are termed "fungicides. " Insecticides are roughly divided into two forms — those that kill by contact and those that I kill when eaten.. The fungicides are also j of two kinds, depending, upon the character I of the fungous diseases which they are mii tended to check — whether thcee which grow i on the surface of the parts attacked, and f which have their mycelium exposed,, suoh l as common mildew of the grape; or tbcSe | which grow wholly within. tfe& plaint tissues, | and which have their vital part 3, the my- ' oolium, wholly protected from man's attack, suoh -as' apple scab. The cheapest rnebhod of applying, and the most ■effectual, as a rule, is in the form of a misty spray — that is, by the use of water as a carrier or distributing agent. Though water is the- usual medium to get the poison upon the plant in an everf-and thorough way, still, it is to be understood that whenever it ia possible to apply a poisonous dust as "evenly and cheaply on the under, as well as the upper surface of the leaf, there is no reason why this should riot in all respects b© as effective ag a spray. The common sulphur bellows is an illustration of an effective dust carrier, or, distributer, for. the application, k of fungicides and insecticides, such, as sulphur to vines, for the purpose of combating mildew,or lime as a contact poison to destroy -the-pejir slug or leech. In regard-to- metkojpls advocated for controlling fungi, it may be well to explain that the remedies for diseases of plants are baaed upon the character and life history of the particular parasitic trouble with L which we havo to deal, or in non-parasitic I troubles upon the particular conditions which give rise to disease. These measures are based upon cocmmonEense reasonings derived from the known relation of oause and effect:. If soil is too -wet, drain it. If overbearing weakems plaints, prevent it by thin- ! ning the fruit. In the domain of parasitic i contagious diseases we Lave those* measures | which destroy the supply of spores or I germs, as well as those which should avoid | the conditions of danger by rotation and planting in new land. These are based on ,th© behaviour of the parasites. j In. addition we have the numerous in- ! , stance"!" cf prevention by the üß© of fungi- | cides. Here we supply some substances which will destroy spores already present, or prevent their groVti^. end parasitic development when deposited,, a-3 with fungous troubles generally", upon fruit and j foliage. For the latter class there has bsetfi I found a certain nearly insoluble copper • Gcmpound, copper hydroxide, which is pro- ' duceo! iii Bordeaux mixture, to remain longer I upon these~ paiiS *n«l be still more effec- : tive than any other" OCmpound. For such purposes the insoluble or* soluble .character is he<re, an advantage ~in--^^f ru^" ing the interval De-tweeai the applicaEioiniof the fungicides. As the ripening period of the fruit *Jspi i o i aoli-3Sj snoro soluble compounds, such as amtnoniacal carbonate of coj>per solution, which will not r&rnain en the ripe fruit, will find application, but here their effective period is shorter than that of the Bordeaux mixture. Thes© mixtures are all preventive moi*e than curative. The results attained by able investigators

as regards remedies for fungous diseases as well as for the control of the depredations of insect pests huvo been remarkable within a few years. Tho power of self-help given to the farmer and fruitgrower by thes© investigations is certainly very great, and these advances possibly constitute our knowledge of the life history of' insect pests and plant diseases and their remedies. Bofor© dealing fully with tne latter it may be well to point out that tihe "tendency to buy insecticides and fungicides ready made has resulted in bringing upon the market a large number of more or loss effective mixtures for which everything is claimed, and at prices several times the value of the active material contained in them. In thes© notes the standard insecticides and fungicides useful in actual practice, or which should be known to all orchardists, will be briefly touched upon. Proprietary mixtures, however good, are not dealt with except incidentally, because their cost is, so far, totally prohibitive for large areas, and because none of them exceed in effectiveness th© well-tested standard remedies. While as a rule materials with fancy names are to be avoided, since they always cost more than 'they are* worth, still it ie desirable that the effective standard remedies should bo put up by reliable firms, so that there is little or no trouble involved in their after preparation for use. These should be sold under their true names for what they are worth.. The advantages of the home mixtures are their low cost and their known effectiveness.