142 MASSACHUSETTS HORTICULTURAL SOCIETY 



Seeds as Carriers of Disease. 



Investigations by the writer have definitely proved that anthrac- 

 nose, Glomerella rufomaculans, may be directly carried with the 

 seed. It is also very probable that " streak" too is transmitted in a 

 similar way. Seeds are also carriers of spores of numerous saphro- 

 phytic fungi, which are unable to produce disease on living plants, 

 but capable of rotting the seed when they lay too long in moist soil 

 while germinating. To overcome this difficulty, the seed should 

 be soaked in a solution of 5 parts of formaldehyde in 95 of water, 

 from two to five minutes. This treatment will also kill spores of 

 anthracnose which may adhere to the surface of the seed coat. 

 The treatment will not reach the interior of infected seed. These 

 should be carefully picked out and burned. 



In storehouses, sweet pea seeds are often ruined by a little insect 

 known as the "drug-store beetle." This pest, however, may be 

 easily kept in check by fumigation with bisulphide of carbon, used 

 at the rate of one pound of the chemical to each 1,000 cubic feet 

 of space. 



Methods of Control. 



Steam sterilization in the greenhouse is the best means of making 

 a soil safe for sweet peas. Much has already been said and written 

 on how to steam sterilize a soil and the advantages derived from it. 

 Prospective growers will do well to install a heating plant with 

 facilities to generate steam. The establishment of such a plant 

 will more than pay for itself as it will put on a sound basis the safe 

 and profitable growing of all greenhouse crops. 



Where steam facilities are lacking, the formaldehyde treatment 

 is the next best means of soil sterilization. Dissolve one pint of 

 pure formaldehyde (sold as 40% pure in all drug stores) in 20 

 gallons of water. With a watering can apply one 'gallon of the 

 solution to every square foot of bed space. This soil treatment is 

 usually done a week to ten days before planting. 



To control mildew, spray with a solution of potassium sulphide, 

 also known as liver of sulphur, one ounce in three gallons of water. 



