24 The Bulletin. 



Cause. — This trouble is caused by a species of microscopic worm, 

 Heterodera radiciola, belonging to the group of Nematodes. The females 

 are very much enlarged during egg-laying, and may be barely seen on 

 breaking across a knot as pearly white bodies one-half the size of a pin- 

 head. The worms may live in the soil for months, but quickly die in 

 galls after the death of the plant. A generation, from egg to egg, is 

 about a month, and a female usually lays several hundred eggs. To 

 nourish in the soil the organism requires: (1) warmth, (2) loose texture 

 of the soil, (3) moderate moisture, and (4) proper food plants. 



Dissemination.— The worms can live over winter in the more pro- 

 tected parts of the soil, or in the galls on perennial plants. They are 

 readily transported to distant places in infected nursery stock, mainly 

 fig, peach or mulberry, or in the roots or adhering soil of annual plants 

 for transplanting, or in Irish potato tubers for seed. For shorter dis- 

 tances the usual agencies are running water that washes the surface soil, 

 hoofs of animals, wheels of vehicles, farm implements, and men's shoes. 

 Possibly winds and manure may be less successful disseminators. The 

 worms can move through the soil, but at a rate of only a few feet a 

 season. 



Infection. — The larval worms enter the young tips of the roots, and 

 the irritation they set up causes the gradual development of the gall as 

 the part grows older. The list of susceptible plants includes several 

 hundred of all sorts of plants. The field crop plants that are practically 

 resistant are rye, winter oats, wheat, corn, peanut, Iron cowpea, and 

 velvet bean. Crab-grass and beggarweed are also highly resistant. 



Control. — Avoid transfer of infected soil. Regulate washing of soil 

 by using embankments. Clean implements in going from an infested 

 spot. Areas can be most quickly cleared of the infestation by keeping 

 the land absolutely bare for two years. But many soils can not be 

 treated thus, and the method is expensive. The next most effective one 

 is to plant for two years in resistant crops, as winter rye or oats followed 

 by Iron cowpeas or peanuts or velvet beaas ; and repeat the second year. 

 Susceptible weeds must not be allowed to grow. If a winter grain is 

 omitted, plow in the fall, cultivate bare the next spring until time to 

 plant the resistant legume. Some reduction can be accomplished by 

 breaking the land deep in dry weather and allowing it to dry out as 

 much as possible. Allowing the land to grow up thick with crab-grass is 

 good. Proper fertilization to make up for soil deficiencies has a good 

 effect on the crop and may enable it to develop in spite of the nematodes. 



LEAF TOBACCO SALES FOR MARCH, 1913. 



Pounds sold for producers, first hand 1,669,630 



Pounds sold for dealers 165,661 



Pounds resold for warehouses 130,947 







Total 1,966,238 



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