4. Overfeeding ... Begonias require ju- 
dicious feeding in order to produce large 
well formed specimens, but overfeeding 
causes perhaps more damage and short- 
ens their lives more than any other fac- 
tor. The quick acting fertilizers such as 
fish-meal and fish-emulsions are of or- 
ganic nature and can hardly do damage 
unless used in excessive quantities. The 
first sign of overfeeding is a rich bluish- 
green color of the leaves which curl un- 
der. The plants will produce distorted 
flowers smaller in size, but gradually as 
the nitrogen in the soil diminishes, they 
will come out of it and perform nor- 
mally. If chemical nitrogen is used in 
such form as nitrate of soda, sulphate of 
ammonia or nitrate of potash, the plants 
simply burn up if overfed. The growth 
will be stunted with small flowers or 
none, and upon maturing the tubers, 
you will find them completely petrified. 
The ideal feeding is to keep the plants 
always slightly hungry by giving them 
light doses of liquid fish-meal or any other 
commercial fertilizer recommended for 
tuberous begonias and religiously follow- 
ing the directions prescribed on the con- 
tainers. If foliage is blue-green withhold 
feeding as they are receiving too much 
nitrogen. Start feeding again when the 
foliage is a soft green color. Very pale 
green foliage is a sign of a deficiency of 
nitrogen and requires increased feeding. 
Rotting of plants . . . The tissue of 
begonia plants is quite sensitive to any 
decaying material which they contact. 
If young plants are set out in a soil 
heavily enriched with manure and the 
decaying parts of the manure come in 
contact with the stem, the plant will 
often rot off at the base. This happens 
more in warmer regions especially with 
high humidity and seldom appears un- 
der cool conditions prevailing along the 
Pacific Coast. A little clean soil or sharp 
sand placed around the stem when plant- 
ing seedlings will prevent the rotting off 
to a great extent. When flowering, the 
plants should be kept clean of all the 
debris of the old flowers and flower stems. 
Flowers should be removed leaving all 
of the flower stem or if cut, as much of 
the stem as possible, as the open wound 
immediately starts molding. If a stem 
is left long enough, it will mature and 
fall off from the main stem before the 
mold can reach its entire length. If cut 
too short, the mold will infect the main 
stem and if not checked, will decay the 
whole plant eventually. Old petals falling 
in the crotch of the leaves may start mold 
in an area which could be scraped clean 
with a knife, dried with a cloth, and 
dusted over with zerlate so it can heal. 
If the main stem is badly molded, it can 
be cut off below the infected part or even 
completely off if necessary. The plant 
should be kept slightly drier as it will 
send new shoots out as a rule trying to 
recover its health. In this way tubers can 
be saved and although weakened, they 
may perform well again the following 
year. If stem rot is not checked, it will 
go all the way down into the tuber and 
destroy it completely. 
Diseases and insects . . . Begonias 
are comparatively free of ills or at least 
they were until a few years ago. The only 
serious infection in the past was cycla- 
men mites which was rare rather and 
confined usually to greenhouses where 
many other plants were grown. The first 
sign of it is rusty brown streaks on the 
foliage and stems, the buds turning brown 
in the very young stage and falling off. 
An effective control can be had by spray- 
ing with various insecticides recommen- 
ded for red spider and mites. 
Bacterial leaf-spot appeared several 
years ago and attacks the plants chiefly 
in the greenhouses where there is high 
humidity and not enough aeration. It is 
most damaging to the young seedlings in 
their germination stage, and we have 
been controlling it with a weak solution 
of Greenol, spraying every five days until 
the plants reach the size for outdoor 
planting. [t seldom attacks plants when 
they are larger and hardly ever if they 
are grown outdoors. 
Mildew, appearing for the first time in 
1951 in isolated areas and spreading 
everywhere since, is perhaps the most 
serious enemy of tuberous begonias so 
far. Preventive Dusting with Sulphur 
Dust has given very good results, control- 
ling the mildew well. Well grown plants 
will resist disease to a great extent. Keep- 
ing the foliage dry—especially at night 
also prevents the spread of any fungus 
disease. 
Strawberry-weavil is wide spread par- 
ticularly in the north, ang the damage 
to the begonias is caused by the larvae 
of the brachyrhinus beetle during sum- 
mer months. The beetles emerge from 
their dormant stage in early May and 
June laying their eggs all summer long. 
The eggs, which are deposited around 
the stem of the plant, hatch rapidly, 
living in their first and second stage on 
decaying material such as leafmold and 
manure. It is in their third, fourth, and 
fifth stage as the larvae gets larger that 
it burrows into the tuber, tunneling back 
and forth until the bulb is completely 
destroyed. The only effective control is 
feeding with a mixture of three per cent 
calcium arsenate in bran or apple bait 
spread among the plants during May and 
June when the beetles feed and before 
the egg laying period begins. 
