a number of other crops. Many prevalent brush and herbaceous weeds of grazing lands, 
watersheds, and forests cannot be controlled with present herbicides and other methods. 
Johnsongrass, nutgrass, Canada thistle, quackgrass, field bindweed, tall larkspur, 
alligator weed, pond weeds, and other perennial weeds are not controlled satisfactorily. 
Effective, economical, and safe control methods are not available for controlling most 
aquatic and ditchbank weeds of farm drainage and irrigation systems. 
These problems can be solved by strengthening research to synthesize and develop 
more efficient low-cost herbicides and then to devise methods for their practical and 
safe use. Basic understanding of the physiological, biochemical, and ecological re- 
quirements of the crop plants and weeds involved is prerequisite to devising chemical 
control methods for many weeds. 
Growth Regulation--Many ornamentals cannot be propagated efficiently because of 
the lack of suitable root-inducing chemicals. Heavy losses of seed from many forage 
legumes could be prevented if satisfactory growth regulators were available to prevent 
shattering before harvest. Frost damage to fruit trees and quality deterioration of forage 
cut for hay could be prevented if satisfactory chemicals were developed for regulating 
maturation. 
These needs could be fulfilled by additional researchto understand the life processes 
involved in such phenomena as root induction, abscission of plant organs, and tissue 
maturation, and then synthesize and develop compounds to induce the plant response 
desired. 
Nematodes--Control of nematodes on growing perennials with economical, low- 
phytotoxic nematocides is the biggest unsolved problem in nematology in spite of limited 
progress with current materials. Plant parasitic nematodes that limit efficient production 
of many agronomic and horticultural crops cannot be controlled because of high cost of 
present nematocides. 
Increased research is needed to develop more effective, low-cost, and low-phytotoxic 
nematocides for controlling nematodes on living plants. Attention should also be given to 
the development of chemicals and methods for treating nematodes on roots several feet 
below the soil surface. Possibilities include low-phytotoxic chemicals which can be applied 
to the plant foliage, translocated to the roots, and then kill or repel nematodes. The 
synthesis and use of possible attractant chemicals in the soil might interrupt nematode 
feeding and reproduction activities sufficiently to make them disappear. 
Plant diseases--No effective methods are available for controlling most root -rotting 
fungi. The general lack of plant resistance to the parenchyma-invading root-rotting fungi 
makes the need for chemical control methods especially urgent. Systemic seed-treatment 
chemicals and improved soil fungicides are needed for controlling damping-off and other 
seedling diseases of crop plants. 
Bacterial plant diseases are not adequately controlled with present methods. The 
pear industry in most of the United States could regain its earlier stability and impor- 
tance if effective, low-cost therapeutants were available to control fire blight. Present 
antibiotics appear erratic and too costly for the control of fire blight and certain other 
bacterial diseases. 
Plant breeding for resistance to cereal rusts and other diseases needs to be sup- 
plemented with low-cost, translocatable, and effective therapeutants to kill the organisms 
within plants or inhibit their reproduction and spread. Concentrated effort should be 
made to complete toxicity studies on the promising nickel compounds as soon as pos- 
sible. 
Virus diseases are not controlled with present materials and methods. Research is 
needed to develop methods for screening chemicals capable of eradicating or arresting 
virus spread within plants. 
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