Grass rust is one of the problems that can befall your lawns. It most often appears in the form of orange-yellow spots, which then slowly turn into raised oblong piles with red (or reddish) spores. If the plague is strong or sudden (so that you do not have time to prevent it), the grass first loses its color and then withers.
It should be noted right away that if the lawn takes on a pale green or yellow color, it does not necessarily mean that it has been attacked by rust. Maybe it just changed color due to unfavorable weather conditions (heat and drought) or insufficient care (poor care).
The fact that rust appears more often in April and May can help in distinguishing, but this is not a rule. Rust most often occurs on grassy areas that are in the shade.
The cause of rust in most cases can be poor grass care (especially lack of nitrogen!). This, of course, means that you need to water your lawn regularly, as well as feed it. Watering should be done thoroughly, but not too often. Special quality lawn fertilizer is recommended for top dressing. Mowing is also important – you should avoid mowing too low. Read more information about soil preparation for planting grass here.
Types of rust
In Croatia, yellow rust (the most common type) has been known since 1928, and four major epidemics have been recorded so far. During these epidemics, grass rust appeared in late autumn or spring, and disappeared as soon as the temperatures rose.
The big problem with grass rust is that it spreads to other plants, primarily to cereals such as wheat, barley, rye, etc. Rust can be prevented by applying fungicides, but in order to do this successfully, you need to recognize the type of rust. In the following, we will briefly describe three types of rust:
Yellow rust
Yellow rust attacks all above-ground parts of cereals such as wheat, barley, rye, rye and oats. With this type of rust, the changes are first noticed on the plant’s leaves and chaff. Changes, albeit less often, can also be seen on the stems and leaves of the plants. If the pericarp of the seed becomes infected, the grain will be stunted.
Also, small yellow pads appear on the leaves, and the further the infection progresses, the pads begin to form a series, and a yellow line is visible. Such lines are parallel to the edge of the plojka, and extend along the entire plojka. At first, these lines, i.e. the pads, are covered by the epidermis, but it cracks over time. Very quickly necrosis and drying of parts of the leaves occurs.
The mold of the plant takes on a brown color (partially or completely). Yellow pads appear less often on the outside of the chaff, but they are not absent on the inside. Towards the end of the growing season, black pads containing teliospores appear and are covered by the epidermis. Yellow rust often appears in Western European countries. In order to prevent this pest in a timely manner, it should be remembered that it appears earlier than other diseases.
Black rust
Black rust is a grain disease of wheat, barley, rye, rye, oats, etc. With this type of rust, the symptoms are first noticed on the blades and leaf sheaths. Symptoms can also appear, but less often, on the plant’s stem. Just as the yellow pads were the yellow pads in question, here they are slightly raised reddish-brown pads (uredosors), and they contain spores that transmit the infection. During the growing season, up to several generations of spores are formed. The pads are initially approximately 1 cm long and elongated in shape. Like the yellow rust pads, these also form a line.
What is specific to black rust is the torn epidermis that surrounds the pads. Speaking of black rust, we talked about the appearance of reddish-brown pads, so you may wonder why this disease is called black rust. Namely, the pads turn black during the time of milk ripening (when the grain takes on a yellow color). Then another type of spore, teliospore, is formed in them. They cannot infect the cereal they are on, but they can infect the intermediate host barberry.
Brown rust
Brown rust is also a disease of cereals such as wheat, barley, rye, rye, oats, etc. The symptoms of this type of rust are first observed on the upper side of the plant. Those symptoms are, you guessed it, pads. These pads are light or dark brown in color and are irregularly scattered on the floor. They are round in shape and quite smaller than black rust pads (size even from 1 to 2 mm). Unlike the pads of yellow and black rust, they rarely form a line, this happens only in the case of a strong attack of this disease. And in these pads, of course, there are spores that transmit the infection. In the second part of the vegetation, round black pads covered with epidermis develop on the underside of the plant. This type of rust is quite more common than black rust.
Although each of these three types of rust has different symptoms, prevention is more or less the same for all of them. You should follow the forecasts and pay attention to the weather conditions that favor the development of fungi – the causative agent of rust, and accordingly apply certain fungicides (they can be used even before flowering!).
This applies most of all to yellow rust, which at the same time appears most often in Croatian areas (and areas of Western Europe).
Therefore, rust, in addition to damaging the appearance and health of your lawn, can also spread to cereals, most often wheat in the Croatian area. Because of this, it can cause problems for farmers.
By regularly monitoring weather forecasts and timely application of fungicides, you can prevent the occurrence and development of this disease. As far as grass is concerned, not every change in grass color should be confused with rust, but you should be careful, water and mow your lawn regularly.
Author: SV, Photo: Pexels/Pixabay