CERTAIN INSECT AND FUNGOUS PESTS. 



415 



rolling of the margins of the leaf, and by a certain stiff- 

 ness due to a peculiar straightening of the midrib. These 

 leaves turn yellow in early summer, and fall very readily. 

 The bunching of the leaves is conspicuous and makes 

 the trees noticeable at a long distance. There is not 

 enough foliage to give shade or to hide the branches." 



Trees attacked by the rosette generally drop their 

 fruit early, and while it is still green, but do not ripen it 

 prematurely. Superficially their roots appear to be in 

 normal condition, but the rootlets are dead and shriveled 

 as in peach-yellows. The disease was first noticed in 

 Georgia about ten years ago, and is now quite destructive 

 in portions of that state, as also in Kansas. 



In the accompanying illustrations taken from Bulletin 

 I, Division of Vegetable Pathology, the reader is given 

 an opportunity for noting the differences between healthy 

 and diseased wood, and between characteristic symptoms 

 of the yellows and the rosette. Both diseases, however, 

 must be regarded as violently contagious, and the only 

 safe advice to be given at this stage of our knowledge 

 concerning them, is to root out and destroy promptly all 

 trees affected by them. 



ENEMIES OF THE ORANGE. 



Orange groves in Florida, like the apple-orchards of 

 the north, were once comparatively so free from insects 

 and fungous diseases that any one could raise sound fruit. 

 But now citrus enemies are so numerous that in a few 

 years the business of growing such fruits will probably be 

 confined to those who study spraying methods intelli- 

 gently and use the machine skillfully. 



The "long scale" insect is by far the most injurious 

 enemy in the Citrus county (Florida) groves l/liat I have 

 examined. It closely resembles the oyster-shell bark- 

 louse of our northern apple-orchards, to which it is simi- 

 lar in life, history and habits. In one large seven-year- 

 old grove that I looked over recently, this insect had yel- 

 lowed the foliage everywhere, and the owner estimated 

 that he had lost 1,200 boxes of oranges in consequence 

 of it ; the fruit was falling off before maturity, and rot- 

 ting on the ground. The trunks, branches and many 

 leaves of the trees were covered with the insect-scales. 

 Beneath each scale were numerous eggs which had not 

 begun to hatch. When they do hatch those trees will 

 be literally alive with young lice, and will require 

 prompt attention if the orchard bears any fruit next 

 year. I have no doubt that the kerosene emulsion will 

 prove an effective remedy if promptly applied while the 

 lice are hatching. 



The fact that certain ladybird-beetles — notably a black 

 species having two red spots on the back — feed upon 

 these pests has led many growers to neglect the scales, 

 with the idea that such enemies would keep them suf- 

 ficiently in check ; but this is a mistake, as many of the 

 groves show. 



The red-spider and the rust-mite are the two other in- 

 sect enemies present in injurious numbers. The former 

 is being quite generally destroyed by spraying, while the 

 latter in the groves I have visited has done comparatively 

 little harm as yet, but should be routed in some way 



The fungous enemies of citrus fruits in Florida have 

 received comparatively little attention, although they are 

 rapidly multiplying. Last year Professor L, M. Under- 

 wood, acting under the direction of the United States 

 Department of Agriculture, made a short field study, 

 and published in the Jouynal of Mycology an excellent 

 account of his observations. Mr. Galloway, of the 

 Division of Mycology, hopes soon to send an assistant 

 into the field to make a more extended and careful study, 

 and to conduct experiments with remedies. There is de- 

 cided need of an investigation of this kind. 



One of the commonest of these fungous diseases is the 

 "scab," which " first makes its appearance in the form 

 of whitish or cream-colored spots, usually on the under 

 side of the leaf, but often on the upper side and oc- 

 casionally on the young twigs and fruit. The spots on 

 the leaf are often accompanied by a depression or pit on 

 the opposite side. These parts grow larger and often 

 coalesce ; ultimately they turn dark, and if abundant 

 the leaf becomes badly curled, twisted, or otherwise dis- 

 torted.*" This scab I found abundant in the Citrus 

 county groves, and have received it from other parts of 

 the state. Professor Underwood found it widespread. 

 I do not know that any successful preventive or remedy 

 has been found. 



The leaf-spot is a peculiar disease due to a parasitic 

 fungus which grows within the tissues of the leaf. The 

 spots are of a faded, grayish-brown color. They vary 

 much in size, but are generally not over half an inch in 

 diameter, and have on both surfaces many small black 

 points. This disease does not seem to be considered at 

 all serious by the growers. 



The leaves of many trees which are affected by scale- 

 insects are often covered with a black fungus called 

 " sooty mould." This fungus lives upon the honeydew 

 produced by the insects, and is not a true parasite of the 

 tree. The mold is in a thin layer, which peels off easily. 

 It was first noticed in the orange groves of California. 

 The easiest way to get rid of it is to destroy the insects 

 which produce the honeydew on which it lives. 



"Leaf-glaze" is the very appropriate name which 

 Professor Underwood has given to a peculiar disease 

 caused by the growth of a lichen upon the orange-leaves. 

 It appears in patches of a peculiar grayish color. It 

 does not draw nourishment directly from the leaf, but, 

 nevertheless, is likely to injure the vitality of the tree. 

 I found it quite common in Citrus county. — Cl.^kence 

 M. Weed, N. H. AgricuUural ColU-gc. 



INSECT DISEASES OF CELERY. 



The aggregate damage done to our celery crops by in- 

 sects is hardly worth talking about, and plays an insig- 

 nificant figure when compared with that done by insect 

 foes to many other vegetables. The grower has little to 

 fear from leaf-eaters. The plants are sometimes at- 

 tacked by the cabbage-plusia or "green lettuce- worm," 

 which is the caterpillar of a pretty moth [Plusia bras- 

 siccv). and a ravenous eater. We also find occasional 



*Underwood. 



