_Mosaic._--No organism has been definitely connected with the mosaic diseases of tomatoes, but they are highly infectious, being spread by means of what is called a "virus," which passes the finest filters. It is spread by insects, notably aphids, which carry plant juice, and in the handling of plants, but it does not persist in seeds or in litter. It is wintered on horse nettles and three species of ground cherries. Control suggestions include roguing affected plants, eliminating weeds, and controlling carrying insects. The symptoms are widely various, the most common being mottling of leaves, stunting and malformation of leaflets, which sometimes become fine ribbons or threads, curling, appearance of small brown dead areas, and spots and cracks on fruits. _Damping off_ is caused by various fungi in the seed bed which attack the stem near the surface of the soil and cause the plant to drop over and die. Clean soil, heating of soil, commonly called sterilization, and care in watering are all helpful. It is now common practice to dust seed with formaldehyde dust, or with red copper oxid or with an organic mercury disinfectant. If trouble is serious, a watering with semesan just before seedlings emerge may be helpful. A government bulletin on "Market Diseases of Tomatoes" (Miscellaneous Publication 121, 1932) is an excellent summary with colored plates to help in recognizing the various troubles. Insects _The Fruit Worm_ (Chloridea obsoleta) is probably the worst of the tomato insects, but is not prevalent in the North. It is the same as the corn ear-worm or the cotton boll-worm, and bores into green or ripening fruits. It winters in the soil and fall plowing is recommended for its control. Planting corn as a trap crop is also suggested. The Virginia Truck Experiment Station finds that the addition of two pounds of calcium arsenate to 50 gallons of the Bordeaux used for disease control helps materially. _Cut-worms_ (various species of the family Noctuidae) cause severe losses at the time of field setting. They winter in the soil and are worse when sod has been plowed under, or following other host plants. Poison bran mash is commonly used to combat them, using a spoonful to each plant. Hand picking and the use of paper collars are resorted to on a small scale. Well-hardened plants seem less subject to injury by these pests than tender plants. _Colorado Potato Beetle_ (Leptinotarsa decemlineata) can cause a world of damage to young plants. Arsenical spray or dust will ordinarily control them. The old-fashioned potato bug (family Meloidae), is reported as troublesome in Missouri. When they appear in droves, the only control is to drive them with brush. Arsenical spray or dust is of some value.