Alternaria on apples (Alternaria mali)

Alternaria on apples (Alternaria mali)

Alternaria small apples photographed on the list in 2014 as
a plantation in the area of Posavina

We all know that the greatest damage in the intensive apple production caused all known scab(scab). But in recent yearsappears to us a recent disease called alternaria . This disease can cause, if not controlled, a lot of damage , and personally I predict that it will be only for her to hear in terms of losses in production, which will be caused by this, our fruit growers less famous fungus . Symptoms are visible on leaves and fruits . The disease attacks the apples but also pears . Last year, 2,014 years personally I recordedstrong attacks Alternaria small, in all localities where theholding rainwater over a long period, which led to increased defoliation of leaves , which ultimately resulted in the weaker return blossoming , as well as lower and higher quality crops. Last year I noticed the first symptoms of alternaria in one orchard pears . I noticed that our most victims varieties Gala , Golden Delicious and Braeburn, Pink Lady or other varieties if they are in conditions of high humidity and high temperatures show sensitivity. Since you all want to warn the danger that the apple production brings this disease , I decided to publish an excellent text on this subject and which is the author of our eminent expert in the field of crop protection  Dr. Milorad Subic ., which is hereby thankthe excellent article , which gives an excellent overview of our readers, in order to more closely acquainted with this disease .

Symptoms Alternaria fruit on G.Deliciousa

Photo : Sachbereich Ökoanbau, VZ Laimburg

 Just as I write this, I look at the reports from the meteorological station , where we can see how in the wider region of Slavoniafell from 100 to 200 liters of rain per square meter, and by a further 10 days, metorolozi announce the dry and hot weather, with daytime temperatures around 25 degreesand these are just excellent conditions for the developmentof this disease, because the evaporation of evil could be great, and are particularly at risk apple orchards where the retainedexcess rain water and where they are grown especiallysusceptible varieties . Of theactive substances for combatingalternarijske mottling on apples according to data from the FIS , with us is a registered combination (fluopyram + tebuconazole) - Luna , which is registered and for the suppression of Septoria on pears ( Stemphylium vesicarium ), which could also become a significant danger in our orchards of pears .



From active substances are registered with us on apples alternare should successfulpreventive control (boscalid + pyraclostrobin) - Bellis , (Metiram) - Polyram. The fruit developed countries still are used and Fluazinam and Iprodione. In May and June is desirable to use metiram a July or August, or use Luna Bellis that suppress and rot (Monilia fructigena) Text Mr. dr. Milorad Subic: In most of the world's apple growing areas, with the exception of the Far Japan, scab (Venturia inaequalis) was dominant fungal disease the most widespread fruit species. Although in 1926 alternarijska ticking apple (Alternaria mali) described in North America, after the 1956 season significant economic losses were recorded in apple growing regions in Japan and some other Asian countries (eg. The Republic of Korea, China, Taiwan and India ). For fungal species of the genus Alternaria, we can say that the general spread around the world, a large number of desirable saprophytes that break down organic matter, or in the plant's health described more parasitic species that cause economically important diseases. Thus, in Europe, for example, species alternata was described at the beginning of the 1960s as a parasite of wounds stored apples, and in Slovenia in mid-1970s indicate the type of Alternaria tenuis as parasites pear fruits. Interestingly, in North America until 1987, are not recorded economic damage but only minor occurrence alternarijske mottling apples, and it was thought that the economic harm of Asian forms of fungus Alternaria small arises because of her specific plant poisons or Phytotoxin (aka. "PM toxin") . However, in the late eighties and early nineties of the past millennium Alternaria small becomes increasingly important parasite of apples in certain areas of the United States (eg. North Carolina).

Alternaria recorded 2,014 years in the extremely wet
conditions in Posavina

 On the territory of the Federal Republic of Yugoslavia in 1996 warning of its first appearance, and after a very hot season in 2000 and 2003 suddenly recorded stronger harmfulness of the disease in some sensitive varieties of apple in northern Italy (South Tyrol) and Austria (eg. Gala , Golden Delicious, Pink Lady son. Cripps Pink). Because of the potentially damaging effects of large apple growing European Plant Protection Organization (EPPO) puts the A1 quarantine list (2007). In our country the first time in 2010 prof. Cvjetković associates warning of a possible occurrence and harmfulness alternarijske mottling apples (observed symptoms on the leaves, but the fruit in orchards had not yet reported damage).
In general, the first symptoms of the disease apple observed on infected leaves in the form of small, round or irregular spot diameter of a few mm to 2 cm, first brown and then silver-gray color. It is more infected leaves on the tops of the shoots. The fungus secretes Phytotoxin causing foliage turns yellow later and early disposal (recorded losses of 50% of the leaf mass at the end of the summer). In Italy, bio-tests proved stronger sensitivity leaves apple varieties Gala, Golden Delicious and Pink Lady, while the apple orchards of high technologies on the field of Mala Remeta in Serbia recorded strong emergence on the leaves of the varieties Golden Delicious and Braeburn during the months of July and August 2011th season. Similar ticking on the leaves Apple may arise due nonparasitic causes (eg. Zinc deficiency or poor ratio of potassium + magnesium nutrients: calcium, and phytotoxicity of some "tank-mix" a mix of plant protection products) (see picture). In alternarijske the mottling of the leaves of apple highlighted brown or reddish edge and whitish middle spots that are generally 2-5 mm in diameter. Varieties resistant to the disease, these are considered Jonagold and Mutsu.
Symptoms on fruits appear only at the most sensitive varieties of apples in two different forms: (a) as a ticking fruits Records Lenticels, when the side of the fruit exposed to the sun develop small brown spots with a red ring diameter of 0.5-2 mm (see figure) or (b) only in the varieties of apple with podčašnim channel in the form of top-level (basal) or dark brown rot decay with seed plants (eg. recorded in the varieties Red Delicious, Braeburn, Rewena) ( see picture). These are symptoms of the fruit in Međimurje and the Pozega valley (source Durdica Kšenek) observed in late summer and / or early fall.

The retention of surface water with high temp.
favors the development of Alternaria

The cause of the disease adverse winter conditions survives as sprofitski spawn on fallen infected leaves, the mechanical damage of annual shoots and / or "sleeping" buds. Primary infection in the new season of growth and development of apple are possible at the end of flowering, and are correlated with temperature, wetting of plant organs and precipitation. The infection of the leaves and fruits of the possible range for the air temperature 20 to 30 ° C, and the wetting of plant tissue sensitive lasts longer than 8 hours (for example in the Delicious varieties in laboratory conditions demonstrated that the optimum conditions for infection of leaf wetting represents a period of 5.1 hours at a temperature of 23.5 ° C, after which 0.2% of the leaf area was covered alternarijskim freckles). Hidden or incubation period lasts at the lab a few hours, and the optimum field conditions described symptoms may occur but 24-48 hours after infection. The longer rainy period in June and July with elevated air temperatures certainly favor a stronger spread the disease to early harvesting. Plantations apple covered with nets against hail due to high humidity certainly favor a stronger manifestation alternarijske mottling apples.
The protection measures should draw attention to the apple orchards of high technology (network hail, irrigation system spraying or sprinkling) with very delicate assortment of apples (eg, gala, red and Golden Delicious, Braeburn, Idared, pink lady) above average in the hot, humid and rainy while the summer months, we should expect the emergence of a stronger alternarijske mottling. In such conditions, it is necessary to conduct targeted chemical protection measures applying sufficiently effective fungicides. Older literature states that provide some protection from the surface of the organic fungicides phthalimide (eg. Captan) (in compositions Captan 50 WP, WDG Merpan 80 and the like) and / or dithiocarbamate (eg. Propineb, mancozeb, metiram, ziram) (in compositions Antracol WG, Dithane DG Neotec, Polyram DF, Ziram WG, etc.), which are both used in large scale suppression of apple scab (Venturia).

Alternaria attack and pears
(pears symptoms on the leaves)

 However, recent research from Italy (Alto Adige) show that when the average 14-day treatment spaces in summer their performance is not satisfactory (Rizzoli et al., 2006)! In the chemical control of some economically important and widespread diseases in general other types of plants caused by fungi of the genus Alternaria (eg. A potato Alternaria solani and / or carrots Alternaria dauci) are highly effective active substances from the group of the strobilurin. However, studies conducted in Austria for spraying the primary infection (3x in the period from 31/5 to 21/6) showed that trifloxystrobin (Flint 50 WG and therefore WG) was no less infected (29.8%) compared to untreated leaves (30.0%) (Rühmer et al., 2006). The most effective results in the suppression of the chemical alternarijske leaf spot of apple, Italy and Austria have been obtained by applying the active substance iprodione (eg. In the preparation Rovral FL), fluazinam (in preparation Ohayo SC) and boscalid (DF Cantus in compositions and Bellis WG), while in Serbia effectively during the 2011 season using chlorothalonil (Bravo in preparation SC). In the area of North Carolina in the United States only iprodione was effective enough.  In the Republic of Croatia authorized to use in apples of these active substances has only boscalid in preparation Bellis WG (in combination with pyraclostrobin registered for the last protection against the apple harvest diseases, scab and powdery mildew ), while other products which are not registered can not be used in our orchards. As Regulation 518/2013 of 13 May 2013 amending Regulation 1107/2009 due to the accession of our country to the EU Croatia is classified southern zone of the registration (for example, together with Italy, France, Spain and other countries), we expect soon Registration preparations for example have permission to use in these countries.In addition to direct measures of chemical suppression is possible sanitary measures to reduce the overwintering potential diseases, eg. the collection of leaves, and when raising new plantations choose less sensitive apple varieties. As alternarijska ticking apples relatively new disease in our country, we must warn the owners of plantations of high technology to regular health checks recognize the first occurrence and take measures to prevent economic damage.