Apple scab

Apple scab fungal disease

1. ASSIGNMENT ON APPLE SCAB Submitted to :- Dr. H.C. Negi (Subject Tutor ) Submitted by :- anjna sharma roll no.:- 2151018 m.sc botany 1 st sem.

2. CONTENTS :- INTRODUCTION ETIOLOGY SYMPTOMS DISEASE CYCLE DISEASE MANAGEMENT

3. APPLE SCAB Crop name :- Apple (Malus spp.) Family :- Rosaceae Disease name :- Scab Causaul organism :- Venturia inaequalis INTRODUCTION :- If your apple or crabapple tree develops spotted and deformed leaves, and cracked fruit that drops early , it’s probably apple scab . Apple scab is caused by a fungus, Venturia inaequalis , and is a serious disease of apple and crabapple (genus Malus) trees that spreads quickly and easily. Generally , you’ll first notice it in early spring , when rains, wind, and cool temperatures spread the fungal spores . The disease was reported from H.P. in 1977. Severe epidemic occured in 1973 in J&k and 1982-1983 in H.P. This disease also occurs in Hawthorn and Mountain ash , a similar disease also affects pear and Pyracantha (Firethorn) .

4. ETIOLOGY OF VENTURIA INAEQUALIS Sub Division :- Ascomycotina Class :- Loculoascomycetes Family :- Venturiaceae Mycelium :- Septate , Branched Epidermal :- The ascosopers multiplies in between epidermis . Asexual spore :- Conidia { Formed in chain in conidiophores ) Flame shaped conidia , Hyline , 1-2 celled . Conidiophore :- Simple , unbranched , non septate. Sexual fruiting body :- Pseudothecia Sexual spore :- Ascospores ( oval to boat shaped , yellowish in colour , 2 celled ) celled are unequal , large and small in size { Inaequalis } .

5. ASEXUAL SPORE :-CONIDIA SEXUAL FRUITING BODY :-PSEUDOTHECIA

6. SYMPTOMS The disease usually noticed on leaves and fruits . The fungal disease forms pale yellow or olive green spots on the upper surface of leaves . Dark velvety spots may appear on the lower surface of leaves. Severely Affected leaves become twisted or puckered and have black, circular spots on their upper surface . The spots may fuse and cover the whole leaf. As the disease progresses, the leaves yellow and drop. .

7. On Fruits :- Symptoms on fruits are similar to those found on leaves , although fruit spots may be more distinctly outlined. The fruit develops scabby spots that are tan and sunken. The lesions are brown and may have spores around their margins. Infected fruits become distorted and may have cracks and rough surface. Heavily infected fruit may drop prematurely.

8. DISEASE CYCLE The apple scab fungus overwinters in fallen , infected leaves, and fruit that are left on the ground. From there, it easily spreads to nearby trees in early spring. Here’s how it spreads : Cool, wet spring weather causes the fungus to grow to maturity , when it releases its spores . Rain and wind carry spores, which land on apple leaves and fruit Wet leaves or fruit allow the spores to germinate and grow into leaf or fruit tissue . Scabs begin to form within a few weeks’ Mature scabs produce more spores that are released into the air and readily transmitted by rain splashes and wind The fungus can quickly multiply, spreading from tree to tree and infecting all susceptible trees in just one season.

9. SECONDARY INFECTION AUTUMN SUMMER SPRING WINTER

10. DISEASE MANAGEMENT  Keep plants healthy.  A tree that is watered during dry periods will be better able to withstand periodic defoliation. .   Clean up and destroy infected leaves.  The fungus overwinters on infected leaves; therefore, it is important to rake up and destroy leaves in the fall. Since the spores also travel on the wind, cleaning up leaves may be only partially effective. Prune trees to allow good air circulation.  Allowing for better air movement will allow leaves to dry more quickly and help prevent infection from occurring. Do not use overhead watering.   Apply fungicidal sprays on emerging leaves and developing fruits SULFER can be used but it must be applied before the fungal spores germinate. Chemicals registered for use include   chlorothalonil  ( Daconil ),  copper , ferbam, fosetyl - Al etc.   Replace the tree with a variety resistant to apple scab.  Resistant varieties of eating apples include: ‘Florina’, ‘Freedom’, ‘Gavin ’,, ‘ Macfree ’, ‘ ‘ Novamac ’, ‘Priam ’,’, ‘ Redfree ’, Many resistant crabapple varieties are available at nurseries and garden centre . If apple scab symptoms seen before on the trees , then spraying young , uninfected leaves and fruits can prevent the disease from developing on healthy tissue.

11. THANKYOU