The three rust diseases of apples are the following:
- Apple Cedar Rust (Gymnosporangium juniperi-virginianae)
- Hawthorn Rust (Gymnosporangium Globosum) and
- Quince Rust (Gymnosporangium Germinate)
And they are caused by three fungi that live during a part of their lives on cedars and junipers and during the remainder largely on the apple, the hawthorn, and the quince.
Effect Of Rust Disease On The Apples
Both the apple and the quince rust cause direct and serious losses by the infections on the apple fruit.
While the apple and hawthorn rust are occasionally destructive to apple foliage. Both types of injury are found where red cedars are abundant.
The apple-rust spots on the fruit are orange in color, and the small cups of the apple-rust fungus may be seen on the spots when mature.
The quince rust spots on the apple fruit are sunken and dark green, and the tissue below the spot is killed.
The small cups of rust fungus are absent in fruit affected with the quince rust. The apple and hawthorn rust form their fruiting bodies on the red cedar in the form of cedar apples.
When the cedar apples are wet in the spring, yellow gelatinous horns protrude from them.
The quince rust does not form the galls or cedar apples but fruits in cankers on the twigs, limbs, or trunks of cedar and juniper. These cankers are perennial compared with the short-lived galls of apple rust.
Apple Rust Varieties
Varieties highly susceptible to apple rust are the following:
- Winter Banana
While more than twenty varieties may be infected with quince rust, including:
- Red Delicious
Controlling Of The Three Rusts
The control of all three rusts on apples is the same. It involves:
- The avoidance and removal of the alternate host
- Planting and replacing with resistant varieties
- Spraying for protection against the disease
Effective control of rusts can be obtained by eradicating all cedars and junipers within one-half mile of the new orchard site.
Removal of Cedars and Junipers
Removing nearby cedars and junipers in the established orchard may not be possible or practicable.
Protective sprays are required from when the young leaves emerge until after the petals fall. Sulfur fungicides give only slight to poor control of these rusts.
Ferbam: Iron Carbonate for Control of Scabs
Fortunately, however, iron carbonate (ferbam), as suggested for the control of scabs, is highly effective in their control.
Whether at full strength (one to 1 ½ lb. to 100 gallons) or reduced strength in combination with sulfur (½ to 100 gallons combined with three to four pounds of sulfur).
For dusting, a 10-90 dust of ferbam and talc or a 5-95 ferbam-sulfur dust is effective. Lime should not be used with ferbam.
Application of Fungicide
Control is protective or preventative. Hence, the fungicide should be applied before or during an infection period.
The pre-blossom, mid-bloom, calyx, and first cover sprays, which are most essential for scab control, give good control of these rusts when ferbam is used, as suggested.
These rust diseases do not spread from one apple leaf or fruit to another. All infections on apples, quince, and others must arise directly from the alternate hosts, the cedars or junipers. The susceptible periods of infection are also relatively short.
Ornamental Plants And Flowers
Rust is especially serious for the following:
- Rose mallow
Ferbam is especially effective against rusks, black spots, leaf spots, and fruit diseases. Combined with wettable sulfur, it makes one of the best general fungicides.
Many companies make a combination insecticide-fungicide containing two to four different materials, which are quite expensive but effective against several inserts and diseases.
Mixture For Spraying
Years ago, a homemade “general” or “one-shot” mixture was suggested for spraying.
- Wettable sulfur – 4 tablespoons
- Ferbam – 114 tablespoons
- 50% wettable DDT – 2 tablespoons
- Nicotine sulfate – 11 teaspoons
Water to make 1 gallon … “one-shot” dust suggested for (lowers consists of):
- 1 pound of ferbam
- 8 pounds of sulfur
- 1 pound of 50% wettable DDT
Blue Beauty of Flowers
Viper’s bugloss, Echium vulgare, is a handsome weed that has come to us from Europe.
Bright blue flowers, borne on crowded clusters, have calyxes that are nearly as long as the corollas.
The showy red anthers of the stamens, which project beyond the mouth of the flowers, give them a warm purplish overcast.
Blueweed, as it is also called, grows in waste places from Nova Scotia to North Carolina and west to Ontario and Nebraska. Flowers are a source of honey for bees.
44659 by Calton A. Cartwright