November 22, 1919 



ii i:t icu lt u h b 



447 



SIM'S 



YELLOW 



POLYANTHUS 



Good either for Pots or 

 for Cutting 



$10 per 100 

 $80 per 1000 



WILLIAM SIM 



CUFTONDALE. - MASS. 



DISEASES OF GREENHOUSE PLANTS 



A bulletin issued by the New Jersey 

 Agricultural Experiment Station is de- 

 voted to the common diseases of orna- 

 mental plants. The following general 

 treatment is recommended: 



In the growing of ornamentals in 

 the greenhouse the problem of con- 

 trolling plant diseases is very closely 

 associated with the art of greenhouse 

 management. It is well known that 

 character of soil, temperature, humid- 

 ity, sunlight and many factors are im- 

 portant in successful greenhouse work. 

 These factors influence the diseases as 

 well as the plants. This subject is so 

 extensive that we cannot give more 

 than a very brief discussion at this 

 time. 



Mixed Crops. The failure in many 

 greenhouses can very frequently be 

 traced directly to the growing of differ- 

 ent kinds of plants in the same house. 

 If these plants require different de- 

 grees of temperature, humidity and 

 sunlight, and since the house cannot 

 be regulated to suit all of them at the 

 same time, some must necessarily be 

 failures. 



Crop Rotation. The organisms 

 which cause many of our plant 

 diseases are carried from year to year 

 in the soil. However, many of these 



diseases are restricted to certain 

 plants, some of them attacking only 

 one variety and some attacking two 

 or more varieties. Therefore, it is 

 advisable to practice rotation of crops 

 as far as possible. 



Although this applies more strictly 

 to field and garden crops, it can be 

 practiced to an advantage with many 

 ornamentals, especially those that are 

 grown for commercial purposes. 



Sanitation. It is well known that 

 many diseases are carried over on the 

 roots, leaves and steins of the plants 

 of the previous year. When a disease 

 has been severe on any crop, it is ad- 

 visable to rake and burn the dead 

 plants and rubbish. However, it Is 

 Impossible to destroy all the frag- 

 ments of the old plants, and therefore 

 crop rotation also should be practiced. 

 Many successful greenhouse men pick 

 off and destroy diseased parts of 

 plants and frequently entire plants as 

 soon as a symptom of disease appears. 



Manures and Fertilizers. Manures 

 are the most desirable fertilizer for 

 most crops, but are sometimes the 

 source of very destructive diseases. 

 Many growers throw diseased and de- 

 caying materials on manure heaps, 

 from which the organisms of disease 



are returned to the soil. Litter which 

 has been used for bedding for live- 

 stock is frequently thrown on the man- 

 ure heap and then carried to the soil, 

 thus carrying its disease back to the 

 land. 



Seed-Beds and Soil Sterilization. 

 Seed-beds and cold-frames should be 

 prepared with the greatest care in 

 order to prevent infection of young 

 plants before setting. In most cases 

 manures are used in seed-beds and 

 cold-frames, but the fact that certain 

 diseases are carried in this way and 

 that damping-off organisms thrive in 

 the manure makes it desirable to use 

 nothing but commercial fertilizers in 

 some cases. (Of course when com- 

 mercial fertilizers are used it may be 

 necessary to use artificial heat.) It 

 is advisable to put the seed-beds or 

 cold-frames in a new place each year 

 if possible, but if this is not done the 

 old soil should be removed or both 

 soil and woodwork sterilized. If the 

 soil is removed care should be taken 

 that it is all taken out, and carried a 

 considerable distance away. A small 

 amount of soil left in the beds is fre- 

 quently sufficient to perpetuate the 

 disease. If the soil is not carried away 

 from the bed small particles are likely 

 to be returned to the bed on imple- 

 ments or on the feet or hands of the 



