THE CONTROL OF TOMATO LEAF-SPOT 
soil and yet are kept favorably moist. To what extent parasites grow 
and spornlate on such materials is not known. 
The writers carried on some experiments with Septoria and a 
number of other tomato parasites to determine whether they will 
grow and live over winter on dead weeds, grasses, and other plants. 
The results rej:>orted in this bulletin are on Septoria lycopersici. 
Stems of cotton (Gossypium herbaceum) and of sweet clover (Meli- 
lotus officinalis) and pieces of crabgrass (Syntherisma sanguinalis) , 
mixed field grasses (chiefly Agrostis alba, Phleum pratense, 
Dactylis glomcrata, and Poa pratensis), cornstalks (Zea mays), rag- 
weed (Ambrosia art emisiae folia) , rough pigweed (Amaranthus re- 
trofiexus), lambs-quarters (Chenopodium album), and Eleusine 
indica were placed in 
glass tubes, sterilized, 
and inoculated with a 
pure culture of Sep- 
toria ly coper sici. 
After the cultures 
were kept in the labo- 
ratory 18 to 21 days 
to give them a start, 
they were placed in 
gallon cans closed 
with rubber corks 
a n d ventilated b y 
means of curved glass 
tubing plugged with 
cotton wool. These 
cans were packed in 
rows in an open cold- 
frame exposed to out- 
door temperatures 
during the winter. 
The following spring 
and summer the cul- 
tures were removed from the cans and repeatedly examined. The 
results are summarized in Table 1. 
Fig. 2 
A stage of sun. scald later than that seen in Fig- 
ure 1. showing the typical appearance of such spots 
after a black mold (Alternaria sp.) has grown on the 
surface 
Table 1. — Overwintering of tomato leaf-spot fungus on dead weeds, grasses, 
and crop remains 
Sterilized materials used as culture media 
Condition of cul- 
tures when set 
outdoors 
Condition of cultures the following 
spring and summer 
Age 
(days) 
Growth 
Cotton and sweet-clover stems (tubes plugged 
21 
21 
18 
18 
18 
with cotton). 
Do. 
with sealing wax). 
Sparse 
Fair 
Abundant 
Fair 
Pycnidia and spores fairly abundant. 
Do. 
Mixed field grasses _ ... 
Cornstalks _ .. ... 
Pycnidia and spores very abundant. 
A mbrosia artemisiaefolia 
18 
18 
Pycnidia and spores present. 
Chenopodium alba ... _ .... . . . 
18 do 
Eleusine indica. 
18 
Fair 
Pycnidia and spores fairly abundant. 
