Seed- and soil-borne organisms acting singly or in combination produce the seedling disease complex that is a major threat to establishing uniform, vigorous plant stands of cotton. Since 1936, Beltwide research has reduced losses caused by seedling diseases through the identification of causal pathogens and the development of more effective control measures. Losses from seed-borne pathogens have been reduced by breeding for disease resistance, acid-delinting, grading, and coating planting seed with fungicides. Planting high quality seed is a prerequisite to reducing losses from seedling diseases. The quality of planting seed has been improved by minimizing field weathering and seed production in the irrigated west. Reduction in mechanical damage to seed and the development of improved management-planting techniques have increased the performance of planting seed.

Tremendous progress has been made in the last century in the introduction of pesticides that contribute to increased seedling vigor and yields. Inorganic fungicides, such as copper and mercury compounds, used for disease control were followed by the development of organic fungicides such as dithiocarbamate (maneb) and phthalimides (captan). These classes of protective fungicides control a broad spectrum of fungi through their multisite mode of actions. Systemic fungicides such as benosyl, demosan, and vitavax were developed during the 1950s and 1960s. These fungicides have a more specific mode of action, since they are systemic (mobile) within plants. Systemic fungicides usually used at low application rates have increased the length of protection to cotton seedlings which may result in more vigorous seedlings. Recently developed fungicides such as metalaxyl (APRON), EPIC, and imazalil are more specific in their spectrum of control. Some of these fungicides control fungi through inhibition of sterol biosynthesis. In the future all new fungicides registered for treating planting seed must have a broad spectrum of activity that will control leaf and seedling diseases of major crops. Cost of development and registration of new fungicides prohibits the search for chemicals with limited uses.

Species of Pythium, Rhizoctonia and Thielaviopsis are the primary fungi that cause seed-seedling diseases. Fusarium and other fungi can cause substantial losses under some conditions. Since most fungicides control a narrow range of closely related fungi, combinations of two or more fungicides must be used to control the wide diversity of pathogens that cause the seedling disease complex. Broad spectrum treatments consisting of protective and systemic fungicides should be used since it is impossible to predict the organism(s) that will cause significant losses. In addition to increasing seedling survival, fungicides may increase the rate of seedling growth and yield. The higher rates of fungicides used in the planter box and in the seed furrow than on the seed can extend the spectrum and length of seedling disease control.

Nematodes and thrips can increase the severity of seedling disease in addition to delaying the development of cotton plants and reducing yields. In many cases, a combination of fungicides, nematicides, and insecticides should be used to obtain uniform stands of vigorous, productive cotton plants. Use only the pesticides that are registered and recommended for your area. Always follow the instructions on the label.

Seed should be planted in well prepared seed beds. Soil moisture and temperature should be ideal for rapid germination of seed and subsequent growth of seedlings. Also, warm dry weather should be expected for ten to fourteen days following planting.