Commercial Crop Production Field Crops - Wheat

Transcription

1 Field Crops Wheat Table 1. Symptoms, source of inoculum and management of diseases of wheat Disease Leaf Rust (Puccinia triticina) Stem Rust (Puccinia graminis tritici) Leaf and lume Blotch (Stagonospora sp.) Powdery ildew (rysiphe graminis tritici) Symptoms: Leaf rust is widespread and probably is the most destructive disease on wheat in Louisiana. The leaf rust fungus produces small, yellowishorange pustules on the leaves. These masses of spores turn dark as wheat matures. Infection usually begins on lower leaves and spreads upward. Infected leaves turn yellow and die. anagement: Resistant varieties are the most practical approach, although fungicides may be used (Table ). Symptoms: longated, reddish brown pustules occur on the stem, leaf sheaths, leaf blades and glumes. Pustules rupture the epidermis to expose a powdery, reddishbrown mass of spores. Fragments of epidermis adhere to sides and ends of pustules to give them a ragged appearance. Source of Inoculum: Has alternate host species of Berberis and ahonia where new races may occur, but spread in this area primarily is from wheat to wheat. anagement: Stem rust is a serious problem in localized regions of Louisiana. Resistant varieties are the most practical approach for control of this disease, although fungicides may be used (Table ). Symptoms: The disease appears on the chaff and may be seen as small, irregular, grayish or brownish spots or blotches, which enlarge and become chocolate brown. As the spots age, their centers turn grayishwhite and may include tiny, round, raised black sporebearing bodies. Ordinarily, only a few glumes in a head become infected, but in severe cases the entire head is attacked and turns dark brown. Spots on the sheaths are dark brown and often include most of each sheath. Spots on leaves are light colored and usually surrounded by a brown border. anagement: Varieties differ in tolerance to leaf and glume blotch. Consult variety recommendations. For fungicide recommendations, please refer to Table. Symptoms: Powdery mildew usually is found on leaves but may attack all aboveground parts of the plant. It first appears as small irregular or circular light gray spots on the upper leaf surface. Later, the plant is covered with a floury appearance. Leaves eventually become misshapened and die. anagement: The application of fungicide for the control of powdery mildew has rarely been economical.

2 Field Crops Wheat Table 1. Symptoms, source of inoculum and management of diseases of wheat Disease Bacterial Streak/Black Chaff (Xanthomonas campestris pv. translucens) Fusarium Head Blight/ Scab (Fusarium spp.) Stripe Rust (Pucina striiformis) Takeall (aeumannomyces graminis) Tan Spot (Pyrenophora triticirepentis) Yellow Dwarf (BYDV) Symptoms: Symptoms on leaves begin as dark green, watersoaked spots that eventually become necrotic and develop into streaks. On the heads, black chaff appears as stripes on the glumes, but blackening may be total. anagement: Use crop rotation, clean tillage and pathogenfree seed. Symptoms: The symptoms after flowering appear as a bleaching of the glumes, spikelets, areas of the head or even the entire head. Salmonred or pinkred spore masses frequently form on infected heads. Control: Seed treatment fungicides help but do not entirely eliminate the fungus. Well timed, foliarapplied fungicides can reduce incidence. Symptoms: The first sign of disease is individual yellow pustules, usually at the top of the leaf. Later, pustules develop in rows, giving the characteristic of striped appearance. Leaves, sheaths, stems and glumes may be attacked. anagement: Resistant varieties are the most practical approach for control of this disease, although fungicides may be used (Table 4). Symptoms: Affected plants have shortened, bleached heads that stand erect, and the affected plants are distributed irregularly throughout the field. The stem base is blackishbrown, and the roots show dark discoloration and are extensively rotted. anagement: aintain balanced soil fertility and use seed treatment fungicides (Table 2). Symptoms: Tan spot first appears on the lower leaves as small yellowishbrown spots that develop into oval spots. Lesion centers become tan and usually are surrounded by a yellow border or halo. As the leaf declines, the spots expand and merge into irregular tan to brown lesions. anagement: Deep plow crop residues. Fungicides may be used (Table 2). Symptoms: Leaf discoloration in shades of yellow, red or purple, especially from tip to base and from margin to midrib. Stunting and excessive tillering are noted. White sterile heads may develop. anagement: No adequate controls are available at this time.

3 Field Crops Wheat Table 2. Fungicides available to manage seed and seedling diseases in wheat Product 1 Rate 2 Disease Apron XL LS fl oz Pythium dampingoff Dividend XL Dividend XL RTA 1 fl oz 5 fl oz Loose smut, general seed rots ankocide per Bacterial diseases anex 2.2 oz/bushel Dampingoff Seed rot Seedling blight axim 4FS axim XL fl oz fl oz Dampingoff System 2 oz/bushel Dampingoff VitavaxCT Vitavax 912 oz 912 oz Loose smut 1 Reference to commercial or trade names is made with the understanding that no discrimination is intended nor endorsement of a particular product by LSU or the LSU AgCenter is implied. 2 Rates are the amount of formulation (product) per hundredweight unless otherwise noted.

4 Field Crops Wheat Table. Recommended fungicides, rates and application timing for wheat diseases Target Product Choices 1 and Product Rate Time of Application PHI 4 ode of Action roup 2 Leaf and lume Blotch (Phaeosphaeria nodorum 5 ) Rust Bumper 41.8C Caramba Dithane DF Rainshield Dithane F45 Rainshield Headline Kocide 000 anzate Flowable anzate Prostick Penncozeb 4FL Proline 480 SC Propiax Prosaro 421 SC Quadris Flowable Quilt Quilt Xcel Stratego YLD Tilt Twinline Bumper 41.8C Caramba Dithane DF Rainshield Dithane F45 Rainshield Folicur.6F Headline anzate Flowable anzate Prostick Penncozeb 4FL Proline,,, 1014 fl oz 2 lb 1.6 lb 69 oz 1.6 lb 2 lb lb 4.5 fl oz fl oz 412 oz oz 1014 fl oz 2 lb 1.6 lb 69 oz 1.6 lb 2 lb lb 4.5 fl oz Protect flag leaf but not past Feeke s S 10.5 Protect as flag leaf emerges No later than the beginning of flowering but not past At flag leaf emergence Prior to disease up to Protect flag leaf but not past Feeke s S 10.5 Protect as flag leaf emerges No later than the beginning of flowering but not past

5 Field Crops Wheat Rate Time of Application PHI 4 Table. Recommended fungicides, rates and application timing for wheat diseases Target Product Choices 1 and Product ode of Action roup 2 Propiax Prosaro 421 4C Quadris Flowable Quilt Quilt Xcel Stratego YLD Tilt Twinline,,, 6.5 to 8.2 fl oz 412 oz oz At flag leaf emergence Prior to disease up to When conditions are favorable for disease development Reference to commercial or trade names is made with the understanding that no discrimination is intended nor endorsement of a particular product by LSU or the LSU AgCenter is implied. 2 ode of action groups are determined by the Fungicide Resistance Action Committee (FRAC). Rates are the amount of formulation (product) per acre unless otherwise indicated. 4 Preharvest interval (PHI) is the minimum number of days allowed between the last application and harvest. 5 Formerly Stagonospora nodorum and Septoria nodorum

6 Field Crops Wheat anagement of Wheat and Other Small rain Diseases The North Central Regional Committee on anagement of Small rain Diseases (NCRA184) has developed the following information on fungicide efficacy for control of certain foliar diseases of wheat for use by the grain production industry in the U.S. fficacy ratings for each fungicide listed in the table were determined by field testing the materials over multiple years and locations by the members of the committee. fficacy is based on proper application timing to achieve optimum effectiveness of the fungicide as determined by labeled instructions and overall level of disease in the field at the time of application. Differences in efficacy among fungicide products were determined by direct comparisons among products in field tests and are based on a single application of the labeled rate as listed in the Table 4. Table 4 includes most widely marketed products, and is not intended to be a list of all labeled products.

7 Field Crops Wheat Table 2. fficacy of systemic fungicides in managing disease of wheat and other small grain diseases fficacy categories are as follows: NR indicate Not Recommended; P=Poor; F=Fair; =ood; =Very ood; =xcellent; = Not Labeled for use against this disease; = Insufficient data to make statement about efficacy of this product for this disease. Fungicide 1 Information Class and ode of Action Active Ingredient Product roup 2 QoI Strobilurins roup DI Triazoles roup Fluoxastrobin 40.% Picoxystrobin Pyraclostrobin 2.6% etconazole 8.6% Propiconazole 41.8% Prothioconazole 41% Tebuconazole 8.7% Prothioconazole 19%, Tebuconazole 19% ixed 8 etconazole 7.4% Pyraclostrobin 12% Rate 4 vito 480SC Aproach SC Headline SC Caramba 0.75 SL Tilt.6 C4, 7 Proline 480 SC Folicur.6 F4, 7 Prosaro 421 SC TwinLine 1.75 C Disease Diseases are abbreviated as follows: P=Powdery ildew; SLB=Stagonospora leaf and glume blotch; SLB=Septoria Leaf Blotch; TS=Tan Spot; Stripe=Stripe Rust; LR=Leaf Rust; SR=Stem Rust and; HS=Head Scab (fl oz) P SLB SLB TS Stripe LR SR HS Harvest Restrictions P F, 45 days, 40 days 0 Days 0 Days 0 Days 0 Days Fluxapyroxad 14.% Pyraclostrobin 28.6% Priaxor Propiconazole.7% Azoxystrobin 7.0% Quilt 200 SC4, Propiconazole.7% Azoxystrobin 1.5% Quilt Xcel 2.2 S C Prothioconazole 10.8% Trifloxystrobin 2.% Stratego YLD days Tebuconazole 22.6% Absolute 500 SC days Trifloxystrobin 22.6% 1 Additional fungicides are labeled for disease on corn, including contact fungicides such as chlorothalonil. Certain fungicides may be available for diseases not listed in the table, including ibberella and Fusarium ear rot. Applications of Proline 480 SC for use on ear rots requires a FIFRA Section 2(ee) and is only approved for use in Illinois, Indiana, Iowa, Louisiana, aryland, ichigan, ississippi, North Dakota, Ohio, Pennsylvania, and Virginia. 2 ode of action groups are determined by the Fungicide Resistance Action Committee (FRAC). Reference to commercial or trade names is made with the understanding that no discrimination is intended nor endorsement of a particular product by LSU or the LSU AgCenter is implied. any products have specific use restrictions about the amount of active ingredient that can be applied within a period of time or the amount of sequential applications that can occur. Please read and follow all specific use restrictions prior to fungicide use. This information is provided only as a guide. It is the responsibility of the pesticide applicator by law to read and follow all current label directions. No endorsement is intended for products listed, nor is criticism meant for products not listed. embers or participants in the NCRA184 committee assume no liability resulting from the use of these products. 4 Rates are the amount of formulation (product) per acre unless otherwise indicated. 5 Harvest restrictions are listed for field corn harvested for grain. Restrictions may vary for other types of corn (sweet, seed or popcorn, etc.), and corn for other uses such as forage or fodder. 6 fficacy may be significantly reduced if solo strobilurin products are applied after stripe rust infection has occurred.

8 Field Crops Wheat 7 ultiple generic fungicides available. Products including tebuconazole include: mbrace, onsoon, uscle.6 F, Onset, Orius.6 F, Tebucon.6 F, Tebustar.6 F, Tebuzol.6 F, Tegrol, and Toledo. Products containing propiconazole include: Bumper 41.8 C, Fitness, Propiconazole A, and Propiax.6 C. Products containing propiconazole + azoxystrobin include: Avaris 200 SC. 8 ixed modes of action products generally combine triazole and strobilurin active ingredients. Priaxor is an exception to this general statement and combines carboxamide and strobilurin active ingredients. The wheat section was revised December 201 by Dr. C. Hollier.