Spring flowers herald the change of seasons and bring us joy in the warmer months. Still, disease problems can arise from winter idleness and poor garden hygiene.
Plant pathogens can survive the winter either in the soil or in material left over from the previous season. bacteria and fungi such as Thielabiopsis and Phytophthora. There are also pathogenic nematodes, such as root-knot nematodes.
There are species that live naturally in the soil, and there are soil aggressors that quickly hijack most of the soil’s resources. When the host’s food source is exhausted, its population declines. Crop rotation reduces the pathogen’s access to preferred food sources and is an excellent technique for managing this invader population. Naturally occurring soil microbes live longer in the soil because they have structures and strategies that help them survive when resources are unavailable or they are not fussy about what they consume.
Several soil pathogens are associated with dead plant tissue. Pathogens emerge when the breakdown of plant tissue begins, called necrosis. These diseases are found on apple scapes and black spots on roses.
Some diseases are associated with living plants, making them easier to spot. These pathogens range from leaf spots on his Entomosporium of the Indian hawthorn to bacteria that cause fire blight. Dogwood spot Anthrax hides in infected twigs and fruits, and it is only later that the result appears as diseased spots on flower bracts.
Viruses are also pathogens that affect plants! Rosette disease in roses is caused by a virus carried by insects that spreads throughout the plant and survives all year round. Weeds are another way viral pathogens can survive the winter. Tomato spot wilt virus and cucumber mosaic virus infect in spring because the pathogenic virus that was hanging out in winter weeds transferred to new food sources via aphids.
Some viruses can actually arrive through infected seeds. Examples include spot fungus on tomatoes and peppers, and black rot on cruciferous plants. Seed companies have quality control programs in place to keep abreast of this issue. If you are saving your own seed each year, you should be aware of seed-borne pathogens and monitor for problems to drive out infected plants.
Thankfully, our winters are inhospitable to some of our least favorite diseases, such as Cucurbitaceae downy mildew and rust. . However, increased warmth and decreased cold snaps during winter make it easier for pathogens to survive.
So what do gardeners do? If you have a problem with pathogens in your garden, destroy the diseased tissue with a burning pile or trash can, not a compost pile. to plant crops. If disease problems recur, look for resistant varieties of plants. For ornamental plants, be sure to discard any diseased material, especially spent flowers, rather than placing them under the plant. Finally, don’t let weeds rule.