COLLECTING ECONOMIC PLANT DATA 43 



large seeds, like those of the mango; 12 bulbs, like those of iris or onion: 

 and 20 tubers, like potatoes. 



Each separate lot of propagation material requires duplicate labels, 

 one for the inside and one for the outside, each bearing the collection 

 number and at least part of the data. All writing is best done with a 

 medium-soft pencil. The inside label for cuttings or scions should be 

 an eyelet tag, tied to one of the pieces. For bags and seed envelopes the 

 inside label may be merely a square of paper. 



DISEASED-PLANT SPECIMENS 



A plant collector, especially in a foreign country, can render con- 

 siderable assistance in the study of parasitic fungi if he will give special 

 attention to the diseased plants he encounters. His notes and specimens 

 will be particularly valuable in the case of economic plants, whether 

 cultivated or wild, and especially so where new crops or new methods 

 of cultivation are being introduced. 



It is always desirable to know as much as possible about the parasitic 

 fungi which occur on wild plants, because diseases are often spread 

 from wild plants to cultivated ones. Still further, the fungi attacking a 

 wild plant ordinarily cause little or no damage as long as the plant 

 remains in its natural living conditions, but any or all of these fungi 

 may suddenly become serious factors when the plant is brought into 

 cultivation. This fact is well demonstrated in the case of the South 

 American leaf disease of the Hevea rubber tree. The disease occurs 

 naturally on wild rubber trees throughout the Amazon region and 

 apparently has little importance under such conditions. However, 

 attempts to cultivate the plant in seedbeds or in plantations sometimes 

 have met with disaster by a sudden appearance of the disease. Young- 

 seedlings are especially susceptible, but even mature trees might be 

 killed. 



Kind of Data Needed 



The name of the host plant is important and must be included in the 

 notes. If the host is a wild plant or an unfamiliar crop plant, the collec- 

 tor will need to prepare a pressed specimen of it for identification pur- 

 poses. Supplementary notes for parasitic fungi include any observations 

 as to the extent of damage caused, such as slight, moderate, severe, per- 

 centage, etc.; and the effect upon the plant — leaf spotting, dieback of 

 branches, cankers on branches or stems, root rotting, fruit decay, flower 

 blight, etc. Photographs of diseased plants are desirable, especially if 

 the symptoms are pronounced. 



Suggested Notes To Accompany Specimens 



F-5002 Leaf spot 



On Siv-ietenia (Coll. No. 5002 - 



Fazonda Itataquibinha, on Rio Tapajos, 50 km. up river from junction with Rio 



Amazonas, Estado do Para, Brazil. Nov. 3, 1940. Affecting onlv lower, shaded leaves 



but causing considerable defoliation. Might become important disease if the tree were 



brought into cultivation. 

 F-5343 Dieback 



On cult, rubber seedlings, Hevea brasiliensis. 



Fazenda Perez, 4 km. S. of town of Bledo, near Belterra, Rio Tapajos, Estado do 



Para, Brazil. Dec. 1, 1940. Eight plants affected in nursery of about 500 2-yr. 



seedlings. Tips die back about 6 inches, but recovery is made by new shoots below 



the infected region. 



