Red rust of tea, litchi and guava

This was presented by one of the group of students to our Asst. professors Mr. and Mrs. Poudel (Pathology) in 2017. By B.Sc.Ag Paklihawa IAAS campus, Full phase 6th batch

1. RED RUST OF TEA C/O : C ephaleurous parasiticus It is an algal diseases that attacks both young and old tea plant up to an elevation of 600 masl . Usually epiphytic on leaves. More severe on tea plant grown under sub optimal growing condition, ill drained soils, alkali soils and inadequate or complete absent of shade.

2. Symptoms: Minute rusty spots on the young unfolded tender leaves. Spots roundish and become enlarge upto 10-15 mm. Reddish and hairy spots on upper leaf surface. Old and thick leaves are discolored. In later stage spots spread to stem. Tissues of the stem are killed in patches and cause dieback. The leaves of the infected branches variegate with yellow patches.

3. Disease cycle: The algae produces microspores, rust colored, spore on the surface of leaf. The sporangia are spread by wind and by water splash. The algae may spread from leaves to branches and fruits. Wide range of host, algal leaf spots are recorded on avocado, , citrus, cocoa, coffee, guava, mango, oil palm, pepper, tea , vanilla, and many more plants. Most algal spots develop on the upper leaf surface. Older infection becomes greenish-gray in color. Cephalerous usually does not harm the plant.

4. Management: Avoid plant stress Avoid poorly drained sites Promote good air circulation in the plant canopy to reduce humidity and duration of leaf wetness Removal of infected portion and spraying of Bordeaux mixture in the injured plant portion. spray the infected plant with Copper oxychloride 0.25 %. Destruction of affected plant portions Improving the nutrient status of the soil by the application of nitrogen, phosphorus and potassium.

5. C/O : Cephaleuros virescens . It caused by algal parasite Predominant on litchi Epiphytic on leaves Parasitic in nature RED RUST OF LITCHI

6. Symptoms: the disease first appear on young unfolded tender branches . At first stage, small lesions of velvety white growth appear on the lower surface of infected leaves . On the upper surface, just the opposite site of lesion , chlorotic patches occur. As the leaf increase in size , the velvety growth becomes more prominent and dense.

7. CONT.. Later larger areas of leaves are affected with this growth . Old and thick leaves show various types of malformation like depression and curling. Finally the velvety growth turns light brown to brick red. Spots spread to stem, infected stem become pale and appear unhealthy even from a distance. Disease results in considerable decline in tree vigour and fruit yield.

8. Disease cycle: Algae can survive in stem and old leaves all year around . Algae forms sporangia on infected leaves and stem ,which are exposed to air. Orange colored zoospores are formed inside the sporangia at low temperature. Zoospores are round to oval in shape and are biflagellated . Zoospore swim in water and germinate to form thallus . Algae can survive in stem and old leaves all year around .

9. CONT.. Algae forms sporangia on infected leaves and stem ,which are exposed to air. Orange colored zoospores are formed inside the sporangia at low temperature. Zoospores are round to oval in shape and are biflagellated . Zoospore swim in water and germinate to form thallus .

10. MANAGEMENT: Provide good drainage facility. Promote good air circulation to reduce humidity . Difficult to eradicate the disease after establishment, so pruning and plucking of infected leaves should be done immediately. Six spray of lime sulphur (3 in autumn and 3 in spring)at 15 days interval. Spray 0.3 % copper oxychloride during July to September is effective. Avoid plant stress.

11. GUAVA RUST: C/O: Puccina psidii Guava ( Psidium guajava - Myrtaceae ) rust is the most important disease of guava trees. Young leaves, flower buds, flowers, young fruit and green shoots are infected by  Puccina psidii

12. SYMPTOMS: The pathogen cause orange to red pustules appearing on foliage, young shoots, inflorescences and fruit of guava. Typical symptoms associated with this disease include distortion, defoliation, reduced growth and if severe, mortality. On fully expanded leaves, dark bordered, roughly circular brown lesions with yellow halos develop Severe infection results lesion to coalesce so that almost leaf are covered. Leaf over 40 days are resistant to infection

13. DISEASE CYCLE: Soil and air borne Puccinia psidii is functionally autoecious , and hemicyclic (no spermogonia and aecia ever observed) Teliospore remain dormant in soil germinate to give 4 haploid basidiospore which form germ tube and enter into host epidermis, colonize, and produce dikaryotic urediospore . Urediospore (asexual spore) are disseminated by rain splash for secondary infection. At later stage black teliospore are formed. Temp of 12-25 ºc and high humidity favours infection Disease usually begins to occur at the onset and development of young shoots; leaves that are 40 days or more old have been observed to be more resistant to infection

14. MANAGEMENT: Destruction of infected twigs, leaves and fruits by burning Root stock from sour guava Lower down the high RH and leaf wetness through proper irrigation practices Adjust plant spacing ,fertilization and pruning of trees. Application of fungicides like copper oxychloride 0.2%

15. THANK YOU Kushal Bhattarai Kabita Kunwar Krishna Dumre Kiran Acharya