118 PROTECTION OF PLANTS — 1923-24 



foot in extent two-thirds up the plant. Here the leaves begin to show irregular 

 yellow spots which subsequently turn brown and finally quite dark, being still 

 surrounded by yellowish areas. Later complete necrosis with wilt and drying 

 out occurs. 



The upper growth becomes spindling and distorted, (Plate II) the leaves 

 small and weak with numerous yellowed and minute necrotic areas. As one 

 looks down the rows between the greenhouse tomato beds the spindling growth 

 of the upper part of the plants is very prominent. Infected plants usually 

 linger on in this condition for several weeks, but rarely there is complete wil- 

 ting of the whole plant — following on curling and shrivelling up of the leaves. 



Immediately below the diseased zone there are on the average eight to 

 ten strong, healthy lower leaves. These seldom show lesions, but the shoots 

 which may arise from the exils of these leaves show typical symptoms. 



The necrotic areas on the leaves do not usually conform to any definite 

 arrangement, but any one of the three following types may be observed: First, 

 the speckling may fellow the veins more or less; secondly, the specks may be 

 grouped together — many having coalesced — on both sides of the main vein 

 at the end of the leaf nearest the stem, or thirdly, the specks may be grouped 

 together on both sides of the main vein and extending to the edges and tip 

 of the leaf. 



In the diseased zone, brown, sunken, oblong stripes or splashes are found 

 on the stems (Fig. 1) petioles, flower stalks and calyces. These streaks occur 

 simultaneously with the specks on the leaf laminas, as a rule. 



No yellow streaking has been observed on the stems, as is the case with 

 the leaves, but the lesions appear brown from the first. These are linear, varying 

 in size from one millimeter to several centimeters in length; they enlarge and 

 often coalesce, although this last is a very variable condition. The larger 

 lesions on the petioles have a more water-soaked and sunken appearance than 

 those on the stem. They gradually enlarge, eventually causing the petiole to 

 shrivel, turn brown, and dry out backwards with the leaflets hanging dry and 

 dead. 



The lesions on the sepals are relatively small and not elongated. 



On the fruit are found dark brown, shiny, sunken, irregularly shaped 

 patches, with no definite arrangement. (Fig. 2) In the initiation stage these 

 appear to be greenish brown, but both types occur on the fruit at the same time. 

 They may occur anywhere on the fruit, although in one type they seem to be 

 confined to the stem end. The largest of the patches, produced by coalescence 

 of the smaller ones, frequently possess one or more cracks or slits produced by 

 drying out. Severely affected fruit tend to be deformed. 



An examination of the roots both externally and internally reveals no 

 apparent divergence from the roots of a normal plant, except that perhaps the 

 root system is somewhat reduced. 



Frequently plants are found which show a superficial bronzing on the 

 leaves in the necrotic zone. On examining these either with a pocket lense or 



