406 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



USTILAGO AND TiLI.ETIA. — (1) UstHaf/O 



smut wliu'h destroys all the parts of the 

 flowers, and only leaves of tlie ears of 

 barley and the ehisters of oats the axis and 

 the hulls. (2) The stinking snmt or hunt of 

 wheat Tilletiii, which only attacks the p-ain 

 which it re places by its organs of reproduction. 



UsTILAGt).— Tlie niyceliuiu of the UstU- 

 aginew live hi the inter! ir of the plant ; it 

 gives rise to numerous fertile branches, in- 

 side which the spores are formed, which de- 

 tached form a black powder. These are the 

 dormant spores. Cutila/o Maydis (maize 

 smut) may directly invade the young tissues 

 of the adult plant. None of the other 

 Uxtilagineir can enter the nurse plant ex 'ept 

 at the birth of the latter. The mycelium 

 which develops forthwith in the tissues of 

 the seedling on the level of the groun<l, ex- 

 temls grailually into the whole plant without 

 pcrccptiblyath'i -ting the growth of the latter. 

 It at ter\var( Is tr;u crses t ae whole nurse plant, 

 and whilst life is gradually extinguished in 

 the lower parts of the plant it conceiitrate-s 

 itself towards the top and arrives at maturity 

 in the ears at the end of the period of growth 

 of the plant. The black spores which are 

 formed, and which spread themselves on the 

 adult plants, do not cause the disease. These 

 spores generally pass the winter and may 

 remain, according to circumstances, several 

 years in the latent state. The following 

 spring they germinate (if the conditions are 

 favourable); they can germinate in a few 

 hours ; there is first formed a promycelium 

 which produces sporidia. The latter if de- 

 taclicd from the promycelium are capable of 

 reproducing the disease if they encounter a 

 young nurse plant. They tlieii penetrate it 

 at the base of the stem or the l)eginningof 

 the root. Amongst tlie I'sfi/u'/n these same 

 winter spores, if they arc l)rought into a 

 nutritive medium in a snil manured with 

 farmyard dung, and especially with purin, 

 may multiply like leaven without jtroilucing 

 promycelium or sporides, and live as sajiro- 

 phytes until they meet with the seedling 

 cereal. The spores of TU/rfia are enclosed 

 at harvest time in the interior of the rusted 

 grain and are almost all carried to the granary 

 where they are sjiread over the corn during 

 threshing. Tt is not so with the spores of 

 Ustilaiji). The spores of this fungus being 

 open to the air at the time of the flowering 

 of the cereals, the greater part falls on the 

 soil or is carried away by the wind. At 

 harvest time the seeds only bear few spores 

 on their surface. See Bunt, p. 388. 



UsTiLAGo Maydis (smut of maize). — This 

 smut attacks the fructified maize, not only 

 in the floral bracts where it forms large, 

 unshapely smutty tumours on the panicles 

 of the male flowers, but also on the stems 

 themselves where the amassed spores form 

 bulky excrescences. 



UsTiLAGO Panici Miliacei (smut of 

 millet). — It invades all the parts of the flower 

 of millet and damages them. The spores are 

 formed in the inflorescences when they are 

 yet enveloped in the sheath of the top leaf. 



Vesi'Erus Xatauti.— Greyish longicorn 

 coleoptera, 2 ceiitim"tres in length. The 

 female of tliis coleoptera lays "iOO-SOO eggs 

 in the beginning of wi-iter under the bark 

 of vine stocks. The small larvre issue in the 

 end of April, bury themselves in the soil, 

 and gnaw the roots of the vine. They take 

 three years to reach maturity, and attain 

 the size of the white-worm. This insect is 

 siiread chiefly over the north of Spain, and in 

 France, in the departments of the Fyrenees- 

 Orientales and Aude. Its ravages have been 

 reported, especially in the communes of 

 Baiiyule, Port Vendres, and CoUioure, where 

 it annually destroys from 50-60 hectares 

 (r25-L')0 acres) of vines. 



Wnoi.LY Aphis. Schizoncura hiniijera. — 

 This aphis has great analogy with the phyl- 

 loxera ; it lives like the latter, as well on the 

 roots as on the aerial part of the plaut, but 

 it prefers the liranclies to the roots. It 

 especially attacks the apple-tree. From the 

 winter egg issue, especially in the months of 

 November and December, partheiiogenetic 

 individuals which yield numerous gemma- 

 tions of similar individuals. From 18 

 May to 12 September Kess'.er observed 

 ten generations ; in summer there was 

 a swarm every fortnight. The aphis hatched 

 in August have wings and produce eggs from 

 which issue sexual individuals dejirived of 

 wings and of suckers. After sexual inter- 

 course the female lays a single egg. The 

 woo!ly aphis, distinguished by the tliick down 

 covering them, are grouped in colonies on 

 the branches and on the edge of the wounds 

 ami sink their dart, as shown by Prillieux, as 

 far as the cambium. The a tivity of this 

 part of the wood being soon increased, it 

 gives rise to aVmormal tissue, to nodosities 

 which split deeply and end in forming 

 cancers, which cause the rot of the branch. 

 Kessler and Goethe have observed this dis- 

 ease (Ui apple-tree and pear-tree roots, on 

 which it forms tlie same nodosities. The 

 diseased coiiilition of the trees is known by 

 their pcrisliiiig,aiid their leaves whicii rapiilly 

 turn yellow and fall during summer. The 

 woolly aphis descend on the roots to a depth 

 of 65 centimetres (26 inches). 



Zabru.s Gibbus (zabrus of cereals). 

 French : Carabe ftossw.— Black coleoptera, 

 1^ centimetres long, with an accentuated 

 prominence of the throat. It attacks corn 

 crops in June in the night and devours the 

 milky juice. The larvje are as injurious as 

 the perfect insects ; they are yellow, with 

 cross plates ; they remain hidden in the 

 day in the burrows dug in the soil, and issue 

 at niglit to devour the wheat in the blade, 

 tliey commit their depredations in autumn 

 as well as in spring for they take two to 

 three years to metamorphose. 



Zeuzera /Escai.i (wood leo])ard moth). — 

 The caterpillar of this bombyx lias .uialogous 

 habits to those of the r'(w.w/\ liiiiu)ii'rda 

 {(/.r.) ; it attacks chestnut-trees, (dms, liine|. 

 birches, oaks, apple-trees, pear-trees, ana 

 others ; its life as a caterpillar also lasts three 

 years. 



