Sugarcane Crop DiseasesA Presentation To IPM

Course/FFS Participants By

Mr. Allah Dad Khan Provincial Coordinator IPM KPK

For MINFAL Pakistan

Pakistan

Sugarcane Mosaic

Mosaic symptoms in sugarcane are currently associated with four diseases that are caused by several viruses (Rott et al. 2008). These diseases are the following:

Mild mosaic—caused by Sugarcane mild mosaic virus (SCMMV).

Streak mosaic—caused by Sugarcane streak mosaic virus (SCSMV).

Striate mosaic—caused by Sugarcane striate mosaic-associated virus (SCSMaV).

Mosaic—caused by Sugarcane mosaic virus (SCMV) and Sorghum mosaic virus (SrMV).

Symptoms

Mosaic is identified primarily by its leaf symptoms. As with most sugarcane diseases, the symptoms may differ in intensity with the sugarcane variety, growing conditions, and the species or the strain of the virus involved. In Florida, however, only SCMV has been identified so far.

The most distinctive symptom is a pattern of contrasting shades of green, often islands of normal green on a background of paler green or yellowish chlorotic areas on the leaf blade (Figure 1). Generally, the chlorotic areas are diffuse, but they may be sharply defined in some sugarcane clones infected with certain strains of the virus. The infection may be accompanied by varying degrees of leaf reddening or necrosis. Chlorotic areas are most evident at the base of the leaf. Chlorotic areas may also be present on the leaf sheath but rarely on the stalk. Young, rapidly growing plants are more susceptible to infection than more mature, slower-growing plants.

Leaves showing contrasting shades of green characteristic of sugarcane mosai

Sugarcane Red Rot Disease

Red rot is one of the oldest known diseases of sugarcane. It occurs in most cane-growing countries. Although it continues to be a threat in certain subtropical countries, it is of little concern to the Florida sugarcane grower

SYMPTOMS

Red rot occurs in various parts of the cane plant but it is usually considered a stalk and a seed-piece disease. Its symptoms are highly variable depending upon the susceptibility of the sugarcane variety and the environment. Symptoms may not be readily apparent in the field, especially in the early stages of the disease. In the later stages of the disease, red rot may cause standing cane to "break down" 

Sugarcane Red Rot Disease

Minute water spots quickly turn reddish brown and elongate parallel to the midrib of leaves infected by the fungus Cochliobolus stenospilus, the causal agent of brown stripe disease. The long, narrow stripes, with straight ends and a yellow halo, may reach 75 mm at maturity

Brown Stripe Disease

Symptoms

Symptoms of SCYLV are a yellowing of the leaf midrib on the underside of the leaf. The yellowing first appears on leaves 3 to 6 counting down from the top expanding spindle leaf (Figure 1). Yellowing is most prevalent and noticeable in mature cane from October until the end of harvest in March. The yellowing expands out from the leaf midrib into the leaf blade as the season progresses until a general yellowing of the leaves can be observed from a distance (Figure 2). Eventually, almost all leaves of the plant turn yellowish. Cold and nutrient stress appear to intensify the symptoms.

Sugarcane Yellow Leaf Disease

Symptoms

White "pencil line" extending the entire length of leaf lamina; etiolated leaves; leaf tips drying out resulting in a scalded appearance

Cause Bacterium Comments Disease emergence favored by water

stressed plants Management The most effective method of

preventing the disease is to plant resistant sugarcane varieties; treatment of seed cane with hot water to clean the material prior to planting can help to prevent the disease

Leaf scaldXanthomonas albileneans

Symptoms

Stunted growth of sugarcane stools; profuse production of tillers; shortened internodes; stems thin with narrow, erect leaves; black whip-like structure emerging from terminal bud

Cause Fungus Comments Disease transmitted through infected

setts and by wind Management The disease can be successfully controlled

by planting varieties of sugarcane which are resistant to the disease; disease can usually be eliminated from seed pieces by hot water treatment prior to planting; infected plants should be removed

Sugarcane smut diseaseUstilago scitaminea

Symptoms

Setts not rooting; central soft portion of set has red discoloration which turns brown-black; cavities in infected internodes; In older canes leaves may be yellowing and plant appears withered; cut stem has a strong smell of pineapple

Cause Fungus Comments Primarily a disease of setts; fungus enters

cut ends of stem or through other wounds Management The most effective method of managing

the disease is through the use of resistant sugarcane varieties; if planting varieties that are susceptible to the disease then plant them in dry, well-draining soils

Set rot/ Pineapple diseaseCeratocystis paradoxa

Symptoms

Small water-soaked spots on leaves; elongated water-soaked spots in shape of an eye; straw colored lesions with reddish brown center develop from water-soaked lesions

Cause Fungus Comments Disease emergence favored by cloudy

weather, high humidity and low night temperatures or wet leaves from precipitation or irrigation

Management Disease can be controlled through the

application of appropriate foliar fungicides

Eye spot Helminthosporium sacchari

Symptoms:

 The disease causes wilting of canes. The affected canes show drying of leaves from top to bottom. The cane stems are shrivelled with considerable reduction in quantity and quality of juice. Small black dot-like bodies of disease causing fungus may develop on bud sheaths and hollow portions of canes. Sometimes only a few internodes are affected, but whole stool or only a few canes in a stool may also be affected.

Stem canker (Cytospora sacchari) Butl.

Symptoms: 

The affected canes produce long, black whip-like and coiled or curved shoots, which are covered with a thin silvery membrane, containing masses of chlamydospores of the fungus. The smutted shoots may arise from the top of the cane or from lateral buds. Later on that membrane ruptures and releases a multitude of spores, which contaminate soil and the standing crop. In certain cases, the infected plants remain stunted in growth with increased tillering of little value. The diseased plants are unfit for use.

WHIP SMUT (Ustilago scitaminea) Syd.

Symptoms:

 The disease may be characterised itself on leaves as small lesions, which gradually enlarge along mid rib and assure dark red to brown colour. In severe infection, the leaves become dry affecting photosynthesis

Leaf spot (Helminthosporium spp.)

Symptoms

Wilt symptoms usually appear after monsoon. Infected clumps, individually or collectively, show stunting and yellowing of top leaves. In severe cases, whole clump dries, cane becomes hollow and lighter in weight. Red discolouration in internodes is more intense towards nodes which do not emit specific odour

3. 

Wilt Cephalosporium sacchari

Symptoms

A large number lean and lanky, pale sprouts in the clump appear like a 'bunchy grass'. Nor mal stalks are not formed.

Grassy shoot Mycoplasma like organism (MLO)

Brown Rust Of Sugarcane

Foliar lesions of brown spot, caused by the fungus Cercospora longipes.Mancha café de la hoja, causada por el hongo Cercospora longipes.