NOTES ON PESTICIDES
This information is supplied with the understanding that no discrimination is intended and no endorsement by Cooperative Extension is implied. Pesticide uses indicated in this publication are believed to be in compliance with approved labels as registered with the U.S. Environmental Protection Agency (EPA) at the time of publication. However, pesticide labels are subject to change, and uses may be altered or revoked by EPA at any time. The pesticide user is responsible for being in compliance with laws in effect at the time of use. Current product labels are available from pesticide suppliers. If necessary, call the pesticide regulatory agency in your state for a copy of the current label. The following statements should not be construed as a substitute for reading the pesticide labels, and they are not meant to contradict the labels in any way!
NOTES ON FUNGICIDES AND BACTERICIDES
Agri-Mycin (streptomycin sulfate):17 WP (4-8 ozs./100 gals., see label for other rates) Bactericide used to prevent fire blight. Effective if used the day before, or the day of, a fire blight infection period. Where fire blight is expected to be a problem, the first spray is made after the first blossoms open when weather conditions favorable for the disease are present or predicted within 24 hours. Must be absorbed by the blossoms to be effective, should not be applied just before or during rain. The frequency of repeat applications depends on weather, blossom opening and disease pressure. Routine use to control shoot blight is not recommended. However, application within 24 hours after the beginning of a hail storm is recommended for fire blight-threatened orchards. Thorough coverage is essential for control. Application at concentration greater than 6X is not recommended. Restricted entry interval 12 hours. Preharvest interval 50 days.
Aliette (fosetyl Al): 80% WDG. Foliar application for control of Phytophthora crown and root rot on all apple trees. The material is absorbed by foliage and transported to roots, so that conditions which limit leaf absorption should be avoided. Under moderate disease pressure, apply Aliette 1 to 5 times at 2.5 lbs. per acre at 30 day intervals. Under more severe pressure, such as when soils are wet for several weeks, apply 5 lbs. per acre at 60 day intervals. Aliette is labeled for nonbearing apples at up to 5 lbs./100 gals., but for an individual application, use no more than 5 lbs. Aliette per acre. The upper limit for bearing trees is also 5 lbs. per acre. Do not exceed 20 lbs. of Aliette per acre per season. Aliette should not be used as a longterm, seasonlong solution to wet soils which can lead to Phytophthora root rot, but rather as a way to maintain production until longer term solutions such as drainage or raised beds may be installed on a site. Restricted entry interval 12 hours. Preharvest interval 14 days.
Bayleton (triadimefon): 50% WP (0.5 - 2 ozs./100 gals.). Effective against powdery mildew and cedar apple rust. Not effective against apple scab. Restricted entry interval 12 hours. Preharvest interval 45 days.
Benlate (benomyl) plus protectant: Use 2-3 ozs. Benlate 50% WP with either: [12-16 ozs. Captan 50 WP; or 7.5-10 ozs. Captan 80 WP; or 12-16 ozs. Captec 4F/100; or 12-16 ozs. mancozeb or maneb 75% DF product; or 19 fl. ozs. mancozeb or maneb 4 lbs. a.i./gal. liquid product, or 1 lb. Polyram; or 1 lb. ziram] per 100 gallons dilute. Effective against apple scab, powdery mildew, sooty blotch, fly speck and black rot. Benlate-resistant apple scab is present in some orchards, resistant powdery mildew is suspected to occur. Use of Benlate in more than three applications per season may increase the risk of resistance. Do not apply during rain. For the final application of the season, the 3 ozs./100 gals. rate of Benlate is better for extended preharvest protection against summer disease fungi in the more southern regions of New England where weather conditions are more favorable for disease development. Benlate appears to be somewhat more effective than Topsin-M against sooty blotch and flyspeck. Benlate does not protect against bitter rot. Restricted entry interval 24 hours. Preharvest interval 14 days.
Captan, Captec: 50% WP (2 lbs./100 gals.); 80% WP (1.25 lbs./100 gals.); 4L (1.5-2 pints/100 gals.). Effective against apple scab, black rot, Botrysphaeria rot, Brooks spot. Effective, but limited residual activity against, sooty blotch, fly speck and bitter rot. Not effective against rusts or powdery mildew. Has caused leafspotting and leaf drop when used on Delicious, Baldwin, Stayman and King before 3 weeks after petal fall, especially when combined with sulfur. Not compatible with lime or other alkaline materials. Do not use within 10 days of oil or in extreme cold or heat. If the fruit is to be sold for export, check for possible restrictions on captan tolerance. Restricted entry interval 96 hours, with worker entry allowed after 48 hours with protective equipment. Preharvest interval 0 days.
Carbamate (ferbam): 76% WP. Moderately effective against scab. Use at 1.5 lbs. 76 WP/100 gals. if used alone for scab; 1 lb./100 gals. if used in combination with another more effective scab fungicide. Very effective against rusts; also effective against Brooks spot, black rot and bitter rot. It has caused lenticel enlargement on some cultivars and considerable fruit russet on Golden Delicious. Late-season use causes undesirable blotchy residue. May cause excessive pump wear in high concentrate sprayers. Restricted entry interval 24 hours. Preharvest interval 7 days.
coppers (fixed): Use as an early season scab protectant, and as a bactericide to reduce the population of fire blight bacteria. Some formulations labeled for use a drench to prevent Phytophthora crown rot. Sold under several trade names and formulations. Types include copper hydroxide , copper oxychloride sulfate, copper tetracalcium oxychloride and tribasic copper sulfate. These are called "fixed", because the copper ion is relatively insoluble and less phytotoxic than in other coppers, such as copper sulfate (bluestone) used in Bordeaux mix. In addition to fungicidal activities, these materials are used as antibacterial agents against fire blight. Application must be made as early as possible, no later than full green tip due to fixed copper's ability to cause damage to young foliage or cause russeting on fruit. To further reduce russeting, use the lowest labeled rate of copper, and add hydrated lime at the rate of 2 lbs. per 100 gals. dilute. Efficacy of copper can be improved by adding 1 quart of oil per 100 gallons of finished spray mix. Do not multiply the oil rate for concentrate spray. Fixed coppers may cause damage to young foliage or cause fruit russeting. Restricted entry interval is 48 hours for copper hydroxide formulations; 24 hours for most other copper products.
Dithane, Manzate, Penncozeb (mancozeb, EBDC): Effective against apple scab, rust, black rot, fly speck, sooty blotch and bitter rot. Use only one of the two following programs. Do not mix programs.
Prebloom only: Use 1.2 qrts./100 gals., but no more than 4.8 qrts./acre (Dithane F-45); or 1.5 lbs./100 gallons, but no more than 6 lbs./acre (Dithane M-45, Dithane DF, Dithane WSP, Manzate 200, Penncozeb 75 DF); beginning at 1/4-inch green and continuing at 7-10 day intervals through bloom. Do not exceed 4 applications (19.2 qrts./acre Dithane F-45 or 24 lbs./acre dry formulation).
Extended: Do not exceed 2.4 qrts./acre (Dithane F-45), or 3 lbs./acre (Dithane M-45, Dithane DF, Dithane WSP, Manzate 200, Penncozeb 75 DF); beginning at 1/4-inch green and continuing at 7-10 day intervals up to 77 days before harvest. Do not exceed 7 applications (16.8 qrts./acre Dithane F-45, or 21 lbs./acre dry formulation).
For trees that require 300 gallons or less per acre for a dilute spray, it appears that mancozeb can be used within the amount per acre restriction of the Extended program as a stand alone primary scab fungicide. Staying within the Extended program limit per acre has the advantage of allowing the use of mancozeb after bloom for early summer disease control.
Toxic to fish, do not contaminate bodies of water with drift, runoff, or rinse water. Restricted entry interval 24 hours.
EBDC's (ethylene bis dithio carbamates). This family of fungicides is often referred to as a single group although there are some differences in efficacy between different products. Effective against apple scab, fly speck, sooty blotch, rusts, bitter rot and black rot. The fungicides included in this group are: mancozeb (Dithane, Penncozeb, Manzate), maneb (Maneb, Manex), and metiram (Polyram). These fungicides are restricted to one of two types of application program; Prebloom-only and Extended.
Once an EBDC fungicide has been applied to a tree, you cannot use another type of EBDC fungicide on that tree during the same growing season. If an application exceeds the Extended program per application limit on amount per acre, then you cannot use an EBDC fungicide on that acre after blossoms have fallen.
Kocide: See coppers (fixed).
Maneb, Manex (maneb, EBDC): Effective against apple scab, rust, black rot, fly speck, sooty blotch, and bitter rot. Use only one of the two following programs. Do not mix programs.
Prebloom only: Use 1.2 qrts./100 gals., but no more than 4.8 qrts./acre (Manex); or 1.5-2 lbs./100 gals., but no more than 6 lbs./acre (75DF); beginning at 1/4-inch green and continuing at 7-10 day intervals through bloom. Do not exceed 4 applications (19.2 qrts./acre Manex or 24 lbs./acre 75DF).
Extended: Do not exceed 2.4 qrts./acre (F4), or 3 lbs./acre (75DF); beginning at 1/4-inch green and continuing at 7-10 day intervals up to 77 days before harvest. Do not exceed 7 applications (16.8 qrts./acre Manex, or 21 lbs./acre 75DF).
For semi-dwarf or dwarf trees that require 200 gallons or less per acre for a dilute spray, it appears that maneb can be used within the amount per acre restriction of the Extended program as a stand alone primary scab fungicide. Staying within the Extended program limit per acre has the advantage of allowing the use of maneb after bloom for early summer disease control. The Extended program limit per acre per application may not allow for use of maneb as a stand-alone primary scab fungicide on trees large enough to require more than 200 gallons per acre for a dilute spray. Restricted entry interval 24 hours.
Manzate 200 (mancozeb). See Dithane.
Morestan: Used against powdery mildew and as a miticide. See Notes on Insecticides and Miticides.
Nova (myclobutanil): 40W. Comes in a water soluble pouch. Effective against apple scab, powdery mildew and rusts. Excellent post-infection activity (96 hours), but limited protectant activity (3-5 days). Recommended for use at 1.5-2 ozs./100 gals. dilute, with a minimum 4.5 ozs./acre, even if tree row volume indicates that a lesser amount per acre is required. Use of Nova before tight cluster may not be economically efficient compared to protectant (contact) fungicides. Until late pink Nova may be applied alone, but it is recommended to combine it with a half-rate of a good protectant fungicide. The protectant fungicide may provide improved redistribution activity in cases where spray coverage is incomplete and give better protection of developing fruit. From petal fall on, Nova must be tank-mixed with a protectant fungicide.
If Nova is applied after the beginning of a scab infection period during which the trees did not have fungicide protection, it is important that a follow-up Nova application be made within 7-10 days using the 2 ozs./100 gals. dilute rate. If Nova is applied more than 96 hours after the beginning of an unprotected infection period, then it is ESSENTIAL that at least one, and preferably two, follow-up Nova applications be made at 7-10 day intervals to kill scab that was suppressed, but not killed by the previous application. Restricted entry interval 24 hours. Preharvest interval 14 days.
Unlike contact protectant fungicides, sterol inhibitor fungicides are not significantly redistributed with rain and must be absorbed into leaf tissue in order to be effective. Do not apply during rain. The material must remain on the leaf at least one hour before being subject to washing off. For concentrate spraying, do not reduce the amount of sterol inhibitor applied per acre. Use the same amount as would be applied for a dilute spray. Applications under slow drying conditions are most effective. Spraying at a concentration of greater than 6X is not recommended, especially under rapid drying conditions, because the spray droplets may evaporate before the fungicide has been absorbed into the leaf tissue. Thorough spray coverage is essential for effective use of sterol inhibitor fungicides. If conditions are excessively windy following an infection period, it is generally better to delay a needed spray of Rubigan or Nova until good application conditions are available and increase the dosage if necessary because of the delay, rather than sacrifice good coverage. Because of difficulty in achieving adequate spray coverage, sterol inhibitors are not recommended for use on trees that are over 24 feet tall, or for trees that have overly dense canopies because of poor pruning.
Normally, sterol inhibitor applications should cease at 1st cover; before primary-season scab control can be adequately evaluated. If there is any doubt about the efficacy of the final post-infection application, make a follow-up application within 7 days. To reduce the chance of developing SI-tolerant scab in the orchard, do not use an SI fungicide after 1st cover. Infections which may occur in the last infection period won't show up for at least 9 days. Make sure that protection is maintained during this time, using a fungicide that will protect leaves and fruit from scab, rust and summer diseases.
Penncozeb 75 DF (mancozeb): See Dithane.
Polyram 80 WP (metiram, EBDC): Polyram is effective against apple scab, but does not last as long as the other EBDCs. Polyram is a mild scab eradicant, approximately equivalent to captan. It is also effective against rust, black rot, fly speck, sooty blotch, and bitter rot. In general, Polyram gives a superior fruit finish in sensitive cultivars Use only one of the two following programs. Do not mix programs.
Prebloom only: Use 2 lbs./100 gals., but no more than 6 lbs./acre (80 WP), beginning at 1/4- inch green and continuing at 7-10 day intervals through bloom. Do not exceed 4 applications (24 lbs./acre).
Extended: Do not exceed 3 lbs./acre, beginning at 1/4-inch green and continuing at 7-10 day intervals up to 77 days before harvest. Do not exceed 7 applications (21 lbs./acre). Staying within the Extended program limit per acre has the advantage of allowing the use of Polyram after bloom for early summer disease control. But the Extended program limit per acre per application may not allow for use of Polyram as a stand-alone primary scab fungicide, with the possible exception of very small trees. Restricted entry interval 24 hours.
Procure (triflumizole): 50% WS. Effective against apple scab, rust and powdery mildew. Excellent postinfection activity against scab (72 hours) with limited protectant activity (3 to 5 days). Procure is a sterol inhibiting fungicide (SI), the same type of material as Nova and Rubigan. Procure, and other SI fungicides, are not costeffective if used after primary scab season. The most effective method for use of Procure, based on experience with other SI fungicides, is to limit it to applications during primary season, and use in combination with a half rate of a standard protectant fungicide. The protectant will allow a longer interval between applications, improve fruit protection, and reduce the chance of resistance development. Applications should be at the rate of 3 to 4 oz. per 100 gal., using the higher rate unless scab infection pressure is light. Do not exceed 64 ozs. per acre in a season. Restricted entry interval 24 hours. Preharvest interval 14 days. For more information on the proper way to use sterol inhibitor fungicides, see the last two paragraphs under Nova.
Ridomil (metalaxyl): 2 lbs./gal. EC; 50% WP. Systemic fungicide for preventing Phytophthora crown or root rot. Applied as a drench containing 1 quart of Ridomil 2E, or 1 pound 50WP, per 100 gallons of water. For use in early spring before growth starts, or postharvest, but before the ground freezes. The amount of drench per tree varies by trunk diameter as follows:
Trunk Diameter Quarts of Solution per Tree
less than 1 inch 1 quart
1 to 3 inches 2 quarts
3 to 5 inches 3 quarts
greater than 5 inches 4 quarts
Restricted entry interval 12 hours.
Rubigan (fenarimol): 1 lb./gal. EC. Effective against apple scab, powdery mildew and rusts. Sterol inhibitor (SI) fungicide with excellent post-infection activity (72-96 hrs.), but limited protectant activity (3 days). Recommended for use at 3-4 fl. ozs./100 gals. dilute, with the exact rate depending on the degree of post-infection activity required. The label calls for a minimum of 8 ounces per acre even if tree row volume indicates that a lesser amount is needed. Use of Rubigan at this rate before tight cluster may not be economically efficient compared to protectant (contact) fungicides. It is recommended that Rubigan be used in combination with a half rate of a good protectant fungicide at intervals not to exceed 10 days. The protectant fungicide may provide better redistribution in cases where spray coverage is incomplete and improve protection of developing fruits.
If a Rubigan is applied after the beginning of a scab infection period during which the trees did not have fungicide protection, it is important to use the 4 fl. ozs./100 gals. dilute rate and to make a follow-up Rubigan application within 710 days. If Rubigan is applied more than 96 hours after the beginning of an unprotected scab infection period, then it is ESSENTIAL that the first spray be followed by at least one, preferably two more Rubigan applications in order to kill scab that was suppressed, but not killed by the previous application. Restricted entry interval 12 hours. Preharvest interval 30 days.
For more information on the proper way to use sterol inhibitor fungicides, see the last two paragraphs under Nova.
sulfur: Formulated as wettable powder, flowable, or dust, at concentration of 30-98% sulfur. Sulfur is very effective against powdery mildew, but has short residual activity and must be used every 7 days for good results. Not as effective as captan for protectant scab schedule. Check label for restrictions on use around oil. Certain sulfur labels prohibit use within 30 days of an oil application. Do not apply with liquid captan on sulfur sensitive cultivars. May cause fruit russeting and/or yield reduction when sprayed post-bloom at above 80oF. Restricted entry interval 24 hours. Preharvest interval 0 days.
Syllit (dodine): 65% WP. Effective against apple scab: 3/8 lb. 65 WP/100 gals. Also an effective eradicant for after-infection scab control when used at 3/4 lb./100 gals. Useful against established scab lesions by suppressing spore germination and production. Do not use on Golden Delicious. Has caused necrotic spotting of McIntosh and Cortland fruit. At the 3/8 lb./100 gals. rate, dodine can be used with oil through the early pink stage. "Buttering-out" can occur in "hard" water or when multiple tanks of spray are applied without rinsing the tank. Prone to foaming. At dosage of more than 1/2 lb./100 gals., dodine may cause injury if applied at freezing or near-freezing temperatures, particularly when accompanied by slow-drying conditions. The 1/2 lb. rate may also cause injury if used with Kelthane WP. Check label for compatibility with other pesticides, EC and F formulations in particular. Apple pomace from dodine-sprayed fruit cannot be used for livestock feed. Not effective against rusts, powdery mildew, fruit rots and most summer diseases. Caution: Dodine-tolerant strains of the apple scab fungus have been identified in the northeast. Limiting use to one or two applications per season will help prevent tolerant strain development. Tolerance develops in orchards where dodine is used consistently for several years. In such orchards, discontinue the use of dodine and substitute with another fungicide. Restricted entry interval 48 hours, written worker notification required. Preharvest interval 7 days.
Thiram: 65% WP (1.5-2 lbs./100 gals.). Similar effectiveness to sulfur for controlling scab, fly speck and sooty blotch. Requires more frequent applications than captan. Toxic to fish. Do not contaminate bodies of water with runoff, drift, or rinse water. Restricted entry interval 24 hours. Preharvest interval 0 days.
Topsin-M (thiophanate-methyl): 70% WP and 70% WSB (4 - 6 ozs./100 gals.). Should be used in combination with a protectant fungicide. In combination with a protectant fungicide, use Topsin-M 70% at 23 ozs./100 gals. See Benlate entry for list of combination rates of protectant fungicides. Topsin-M is similar to Benlate in effectiveness, having locally systemic activity, and in ability to induce resistance. Do not mix with materials containing copper or lime. Restricted entry interval 12 hours. Preharvest interval 0 days.
Ziram: 76% DF (1 to 1.5 lbs./100 gals.). Considered only to have "slight" activity against scab, but may be useful as a summer fungicide against fly speck and sooty blotch. When used in combination with a more effective fungicide, the 1 lb./100 gallons dilute rate can be used. Restricted entry interval 48 hours. Preharvest interval 14 days.
On to Activity Spectrum: Apple Fungicides
1996-1997 New England Apple Pest Management Guide