In a perfect world nothing would ever make a flower less beautiful. In a perfect world nothing would ever keep one from blooming. In a perfect world pests would not exist.
Welcome to the real world of pests in your flower bed.The biggest struggle for most of my flowers has been the heat. Those that were not planted prior to the rain at the end of May never had any kinder, gentler weather to become established. They have been pouting over their plight and have grown slowly in protest. The only cures are time, tender loving care and moderating temperatures.
Water is another struggle for many gardeners. Getting it right is difficult. When I first started growing vegetables there were not many choices for watering. Our water turn came once per week. By the end of the season it was a struggle to get enough water down the ditch to wet the soil at the end of the row. The only possibility of overwatering was if you turned too much water down the row and ended up washing the plants away.
Times have changed and most flowers are watered by automatic sprinkler systems. Unlike the vegetable garden where you turned the water down a row with all the same kinds of plants, we now mix dozens of different plants into each bed with little regard to water needs.
Managing watering in flower beds is difficult. Besides the many species that may have different water requirements, the systems are trickier to operate. Unlike turfgrass, with a very even height, flowers come in all sizes in the same bed. The plants near the sprinkler often block the spray and are badly overwatered. Those some distance from the heads may not get enough. Lack of water results in poor growth while excess water causes root rot and other diseases.
Powdery mildew is a common flower disease. Many plants are affected, but zinnias, columbine and begonias are badly damaged. Avoid growing these in heavy shade or where there is poor air circulation. If you still want to grow susceptible crops, preventative sprays of Halt, Bayleton, Benomyl or Funginex help solve the problem.
White mold is an interesting problem that afflicts marigolds, petunias, zinnias and other flowers. The disease causes the plants to dry up and die. This symptom is not unusual, but the disease produces interesting reproductive structures inside the stems. These small black pellets resemble mouse droppings. Preventative fungicidal application may prevent but won't cure the disease.
Root rot is probably the most widespread of all diseases. Most bedding plants and many perennials are susceptible to this problem. Begonias, geraniums, marigolds, petunias, lobelia, vinca, dianthus and pansies are among the most seriously affected. The plants usually stop growing well and then surrounding plants show the same symptoms. Plants often collapse and die suddenly when the weather gets hot and dry.
The causal organisms are usually Phytophthora or Pythium. These are water mold fungi so that should give you some idea of how to control the problem. Strict water management is essential. Keeping the roots wet is a certain invitation for these fungi to flourish and destroy your flowers. In extreme cases, rotate the beds out of susceptible flowers for at least two years and grow plants that tolerate dry conditions and are resistant to root rot. The rot is often aggravated by other diseases that cause similar symptoms.
Rhizoctonia attacks several flowers. The fungus attacks the stem at the base and often shows as dark lesions on the stems. The fungus is most serious when plants are severely overwatered. As with most other diseases, water management is critical.
The most troublesome insect for me this year has been the tobacco budworm. It feeds on my petunias, nicotiana and geraniums. Dipel or Thuricide are the best controls if you start before damage becomes serious. Earwigs also are looking for a meal on my marigolds and some other flowers. Dry out the area and use baits or sprays if the damage is severe.
Spider mites are showing up on many flowers in hot, dry areas. These are not insects, so insecticides are not effective against them. Keep the plants clean and avoid unneeded pesticide treatments that kill the predatory mites. In extreme cases remove the plants or treat them with Kelthane or Vendex.
Don't stop aggressive slug and snail control. They continue to devastate many plantings and need to be taken care of to keep them from laying eggs this fall.
Although our world may not be perfect, flowers make it more beautiful. Learn to control the environment and you can control most pests. Diseases, insects and other pestilences can be kept at bay. Keep the flowers blooming so they will add to the beauty and enjoyment of your garden.