Radish

Radish ashahane
Radish Disease Control Radish Insect Control Radish Weed Control

Introduction

Radish (Raphanus sativus) is a member of the Brassicaceae family, along with cabbage and other brassica crops. Radish is a very old crop, possibly important as early as 5,000 years ago. Present-day radishes include European radishes with relatively small roots as well as the large-rooted white daikons that are enjoyed both as food and, recently, as a cover crop, due to long taproots that can penetrate compacted soil.

Radishes grow very quickly, maturing in 21-28 days under ideal conditions. In cold weather, 40-50 days may be required. Preferred planting dates are early spring and August. The roots (technically swollen hypocotyls and roots) are spicy, due to the presence of glucosinolates, which are sulfur-containing compounds produced by members of the brassica family. High temperatures and a lack of moisture can increase both pungency and the speed of bolting. As a result, production in the spring and fall often results in higher quality radishes than those produced in the summer. Some varieties also have a tendency to become pithy, possibly in response to certain environmental conditions. 

Types and Varieties

Table radishes come in an array of shapes (round, cylindrical, turnip-like) and colors (white, green, red, and black). Daikon is a general term for a group of long, white radishes that need cool temperatures and short day lengths to flourish. Some of these can grow up to 18" long and weigh about 3 lb on average, but can reach almost 50 lb. The black or winter radish is intensely hot. Radish tubers are formed from the basal part of the main shoot and a portion of the root.

Type Varieties
Small, Round

Champion

Cherriette

Cherry Belle

Crunchy King

Crunchy Royale

Early Scarlet Globe

Easter Egg (red, white, and purple)

Fireball

Pearl

Red Satin

Rover
Slender

D'Avignon (red and white)

French Breakfast (red and white)

Miyashige (white daikon)

Nelson (red and white)

White Icicle (white)

Shunkyo (red)
Storage Types

April Cross (Japanese daikon)

Black Spanish (black)

KN-Bravo (purple Korean daikon)

Nero tondo (black)

Red Meat (watermelon)

Summer Cross No. 3 (Japanese daikon)

Summit (Korean daikon)

Watermelon

Soil Fertility

Apply lime according to soil test results to maintain soil pH at 6.0-6.8. Radishes need loose, well-drained soil for easy root expansion. Although daikon can penetrate heavy soils to depths more than 1', the roots will not be smooth, uniform and tender in heavy soils. In stony or very heavy soil, shorter daikon varieties perform better. Because radishes grow so rapidly, a rich, fertile soil is essential. They prefer cool growing conditions (50-65ºF), so maintain a high level of soil moisture to minimize the adverse effects of summer temperatures. Hot weather reduces quality and increases pungency. Late plantings may bolt before edible roots form.

Less nitrogen fertilizer will be needed if legume sod was plowed down or if manure was applied (see Table 1 and Table 7).

Plant Nutrient Recommendations According to Soil Test Results for Radish

SOIL TEST RESULTS NITROGEN (N) - LBS PER ACRE PHOSPHORUS (P) -
LBS P2O5 PER ACRE		 POTASSIUM (K) -
LBS K2O PER ACRE
VERY LOW LOW OPTIMUM ABOVE OPTIMUM VERY LOW LOW OPTIMUM ABOVE OPTIMUM
Broadcast and Incorporate 50 150 100 25-50 0 125 100 50 0-25
TOTAL RECOMMENDED 50 150 100 25-50 0 125 100 50 0-25

Planting 

The seeding rate for table radish is 18-38 lb of seed/A (depending on variety) or 1.4 oz/100 ft row. The seeding rate for daikon radish is 1 lb/A. 

Spacing. Seed radish 0.25-0.5" deep, spaced at 0.75-1" apart within the row (to obtain 12-15 plants per foot of row). Space rows 8-15" apart. It is not recommended to transplant radish.

In the spring, plant as soon as the soil can be worked; thereafter, plant at intervals of about 10 days. Soft, well-tilled ground will result in the most attractively-shaped radishes. Radishes are often planted in 4' wide raised beds, in 6 rows per bed. Use of floating row covers at time of planting will help control flea beetles and cabbage root maggots. Keep soil moist, especially if growing in hot conditions. 

Harvest and Storage

Yield. Some salad radishes and most storage radishes are marketed with tops removed in plastic bags. Bunched radishes are common at farmers' markets and smaller retail operations. Those sold with tops will lose moisture and quality more rapidly than those without leaves. A good yield of bunched table radish is 2,500 dozen bunches (8-12 radishes/bunch) per acre (about 25 bunches per 30 ft of row). A good yield of film-packed radishes (8-oz bags) is about 15-20 bags per 30 ft of row. Daikon may be marketed in cartons or 20-lb plastic bags and good yields range from 15 to 20 tons/A.

Table Radishes. Harvest on time, beginning about 3-4 weeks after seeding when roots are the size of a large marble (depending on variety). Bunch or top, hydrocool, and refrigerate. Topped radishes will keep 3-4 weeks in good, crisp condition if kept at 32º F, 95% RH, and in breathable packaging.

Daikon Radishes. Harvest by hand beginning approximately 60 days after planting. The roots are harvested at about 12-14" in length for the processing market and 2.5" for the oriental vegetable market. Daikon can be sold with or without the tops attached; usually a better price is paid for tops left on the roots. Daikon radishes will last 3-4 months at 32º and 95% RH.

Radish Disease Control

Radish Disease Control ashahane
Radish - General Radish Insect Control Radish Weed Control

NOTE: For the disease control products listed below, a product trade name and formulation are provided for each active ingredient (common name) as an example of rates, preharvest interval (PHI), restricted entry interval (REI), and special instructions. In many cases, there are other products available with the same active ingredient. Please see Table 25 and Fungicides and Bactericides Alphabetically Listed by Trade Name for more information on products with the same active ingredients.

The symbol OG indicates a product is listed by the Organic Materials Review Institute (OMRI) as approved for use in organic production. See Organic Certification section for more details.

Alternaria Leaf Spot (Alternaria brassisicola, A. brassicae)

Alternaria leaf spot does not affect radish roots but can reduce root yields if severe and will reduce the value of fresh-packed plants that retain the foliage. Buy certified disease-free seed or hot-water treat seed. Control brassica weeds and plow under crop debris in the fall. Rotate with non-brassica crops.

  • azoxystrobin (Abound aka Quadris): 6.0 to 20.0 fl oz/A; PHI 0d, REI 4h, Group 11. Do not rotate with other Group 11 fungicides.
  • Bacillus amyloliquefaciens strain D747 (CX 9030OG aka Double Nickel 55OG): 0.25 to 3.0 lb/A; PHI 0d, REI 4h, Group BM2. See label for rates. Suppression only. 
  • Bacillus subtilis Strain QST 713 (Serenade MaxOG): 1.0 to 3.0 lb/A; PHI 0d, REI 4h, Group BM02. Begin applications soon after emergence and when conditions favor disease. Apply in sufficient water to provide thorough coverage.
  • penthiopyrad (Fontelis): 14.0 to 30.0 fl oz/A; PHI 0d, REI 12h, Group 7.
  • cyprodinil plus fludioxonil (Switch 6.25 WG): 11.0 to 14.0 oz/A; PHI 7d, REI 12h, Groups 9 & 12. 
  • pyraclostrobin (Cabrio EG): 8.0 to 12.0 oz/A; PHI 0d, REI 12h, Group 11. Do not alternate with other Group 11 fungicides.

Downy Mildew (Hyaloperonospora brassicae)

This disease occurs worldwide, affects most brassicas, and is most important at the seedling stage. It is an important pathogen on radish because it can infect the fleshy root, causing external black patches, lesions on the root shoulder, and internal grey or black flecking and streaking. The root surface is scarred, prone to cracking or splitting, and unmarketable. Plant resistant or tolerant cultivars.

copper oxychloride plus copper hydroxide (Badge X2OG): 1.0 to 2.25 lbs/A; PHI 0d, REI 48h, Group M1. Begin application when disease first appears or when conditions favor disease.

Seed Decay

Purchase treated seed. Do not use treated seed for food, feed, or oil purposes.

  • azoxystrobin (Abound aka Quadris): 0.40 to 0.80 fl oz/1000 row feet; PHI 0d, REI 4h, Group 11. See label for application rates and directions.
  • Bacillus amyloliquefaciens strain D747 (CX 9030OG aka Double Nickel 55OG): 0.5 to 1.0 lb/A; PHI 0d, REI 4h, Group BM2. See label for rates, at-planting instructions, and restrictions. Labeled for damping-off, seedling blights, and root and crown diseases.
  • fludioxonil (Maxim 4FS): 0.08 to 0.16 oz/100 lb seed; REI 12h, Group 12. For protection against seedborne and soilborne fungi. Does not control Pythium or Phytophthora.
  • fluopicolide (V-10161 4 SC aka Presidio): 3.0 to 4.0 fl oz/A; PHI 7d, REI 12h, Group 43. For Pythium control. Apply as banded spray. Application at seeding may help control downy mildew. See label.
  • mefenoxam (Apron XL SL): 0.085 to 0.64 fl oz/100 lb seed; REI 48h, Group 4.
  • mefenoxam (Ridomil Gold SL): 1.0 to 2.0 pt/A; REI 48h, Group 4. Pre-plant incorporated or soil spray broadcast or band.

White Rust (Albugo candida)

Yield reductions caused by white rust are rare but quality is reduced by the prominent, raised white spore masses on the underside of leaves. On radish, white rust can also infect flower shoots and cause root swellings. Use resistant cultivars where available and rotate to non-hosts where the disease is common. Proper fertility levels, especially of phosphorous and potassium, have been reported to reduce disease.

  • azoxystrobin (Abound aka Quadris): 6.0 to 20.0 fl oz/A; PHI 0d, REI 4h, Group 11. Do not make more than 1 foliar application before alternating with a non-Group 11 fungicide.
  • copper oxychloride plus copper hydroxide (Badge X2OG): 1.0 to 2.25 lb/A; PHI 0d, REI 48h, Group M1. Begin application when disease first appears or when conditions favor disease.
  • pyraclostrobin (Cabrio EG): 8.0 to 16.0 oz/A; PHI 0d, REI 12h, Group 11. Do not rotate with other Group 11 fungicides.
Disease Control

Radish Insect Control

Radish Insect Control ashahane
Radish - General Radish Disease Control Radish Weed Control

NOTES: For the insecticides listed below, one product trade name and formulation is provided for each active ingredient (AI) as an example of rates, preharvest interval (PHI), restricted entry interval (REI), and special instructions. In many cases, there are other products available with the same AI. Please see Table 27 and Insecticides Alphabetically Listed by Trade Name for more information on these insecticides.

The designation (Bee: L, M, or H) indicates a bee toxicity rating of low, moderate, or high. See the Protecting Honeybees and Native Pollinators section for more details.

The symbol * indicates a product is a restricted use pesticide. See Pesticide Safety and Use for more details.

The symbol OG indicates a product is listed by the Organic Materials Review Institute (OMRI) as approved for use in organic production. See Organic Certification section for more details.

Cabbage Maggot (Delia radicum)

Cabbage maggot can be excluded from brassica crops with spunbonded row covers. Cover at seeding and seal the edges with soil to exclude the adult fly which lays eggs at the base of young radish seedlings. Do not plant into land that was planted to a brassica crop the previous year, as this pest overwinters as pupae in soils where larvae infested plants.

See the Cabbage, Broccoli, Cauliflower, and other Brassica Crops insect control section for more information about cabbage maggot.

  • cyantraniliprole (Verimark): 10 to 13.5 oz/A; PHI 0d, REI 4h, Bee: H, Group 28. For soil applications at planting. Suppression only. 

Cutworms

See cutworms in the Pepper and Tomato (Outdoor) sections for more information on black and variegated cutworms.

  • alpha-cypermethrin (Fastac* EC): 1.3 to 3.8 oz/A; PHI 1d, REI 12h, Bee: H, Group 3A.
  • Bacillus thuringiensis aizawai (XenTariOG): 0.5 to 1.5 lb/A; PHI 0d, REI 4h, Bee: L, Group 11. Must be ingested. Apply in evening or early morning, before larvae are actively feeding. Adherence and weather-fastness will improve with use of an approved spreader-sticker. Use high rate at cool temperatures. For resistance management, may be rotated with Bt kurstaki products (Dipel).
  • Bacillus thuringiensis kurstaki (Dipel DFOG): 0.5 to 2 lb/A; PHI 0d, REI 4h, Bee: L, Group 11. Must be ingested. Apply in evening or early morning, before larvae are actively feeding. Adherence and weather-fastness will improve with use of an approved spreader-sticker. Use high rate at cool temperatures. For resistance management, may be rotated with Bt aizawai products (XenTari).
  • beta-cyfluthrin (Baythroid* XL): 1.6 to 2.8 oz/A; PHI 0d, REI 12h, Bee: H, Group 3A.
  • bifenthrin (Brigade* 2EC): 5.1 to 6.4 oz/A; PHI 21d, REI 12h, Bee: H, Group 3A. Apply as foliar spray.
  • carbaryl (10% Sevin Granules): 20 lb/A; PHI 7d, REI 12h, Bee: H, Group 1A. Apply evenly over soil surface.
  • deltamethrin (Delta Gold*): 1 to 2.4 oz/A; PHI 3d, REI 12h, Bee: H, Group 3A.
  • methoxyfenozide (Intrepid 2F): 8 to 16 oz/A; PHI 1d, REI 4h, Bee:L, Group 18. Suppression only.
  • spinosad (SeduceOG): 20 to 44 lb/A or 0.5 to1 lb/1000 sq ft.; PHI 3d, REI 4h, Bee: M, Group 5. Spread bait on soil around plants.

Flea Beetle, Crucifer (Phyllotreta cruciferae) and Striped (P. striolata)

See the Cabbage, Broccoli, Cauliflower, and Other Brassica Crops insect control section for more details on flea beetles that attack brassica crops.

  • alpha-cypermethrin (Fastac* EC): 1.8 to 3.8 oz/A; PHI 1d, REI 12h, Bee: H, Group 3A.
  • beta-cyfluthrin (Baythroid* XL): 1.6 to 2.8 oz/A; PHI 0d, REI 12h, Bee: H, Group 3A.
  • bifenthrin (Brigade* 2EC): 5.1 to 6.4 oz/A; PHI 21d, REI 12h, Bee: H, Group 3A. Apply as foliar spray.
  • carbaryl (Sevin XLR Plus): 0.5 to 1 qt/A; PHI 7d, REI 12h, Bee: H, Group 1A.
  • deltamethrin (Delta Gold*): 1.5 to 2.4 oz/A; PHI 3d, REI 12h, Bee: H, Group 3A.
  • esfenvalerate (Asana* XL): 5.8 to 9.6 oz/A; PHI 7d, REI 12h, Bee: H, Group 3A.
  • imidacloprid (Admire Pro): 4.4 to 10.5 oz/A; PHI 21d soil, REI 12h, Bee: H, Group 4A. Soil applications only.
  • kaolin (Surround WPOG): 25 to 50 lb/A or 0.25 to 0.5 lb/gal; PHI 0d, REI 4h, Bee: L. Suppression/repellence only. Generally compatible as a tank mix with other insecticides.
  • pyrethrin (PyGanic EC5.0OG): 4.5 to 17 oz/A; 0.25 to 0.50 oz/gal, 3 gal/1000 sq ft in greenhouse for backpack sprayers; PHI 0d, REI 12h, Bee: M, Group 3A.
  • spinetoram (Radiant SC): 6 to 8 oz/A; PHI 3d, REI 4h, Bee: M, Group 5. Suppression only.
  • spinosad (Entrust SCOG): 3 to 6 oz/A; PHI 3d, REI 4h, Bee: M, Group 5.
  • thiamethoxam (Actara): 1.5 to 3 oz/A; PHI 7d, REI 12h, Bee: H, Group 4A.
  • thiamethoxam (Platinum): 5 to 6.5 oz/A; REI 12h, Bee: H, Group 4A. Use at seeding or within 24 hours of seeding as an in-furrow or narrow surface band with sufficient water for incorporation, or in drip irrigation. 
Insect Control

Radish Weed Control

Radish Weed Control ashahane
Radish - General Radish Disease Control Radish Insect Control

NOTES: For the herbicides listed below, one product trade name and formulation is provided for each active ingredient along with preharvest interval (PHI), restricted entry interval (REI), resistance management group number, and example of rates and special instructions. In many cases there are other products available with the same active ingredient. However, not all products with the same active ingredient are registered for use in a crop. Always check the product label to be sure that the crop is listed before using. 

See section Soil Fumigation Outdoors in the Disease Management section. Proper use of Vapam can provide weed control and will be more economical if multiple plantings are used.

Stale Seedbed

See Stale Seedbed Technique for information on the use of these herbicides or flaming.

  • glyphosate (Roundup Power Max): PHI 14d, REI 4h, Group 9.
  • pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0.

Preemergent Herbicides (before weeds germinate)

  • dimethenamid (Outlook): PHI 21d, REI 12h, Group 15. Apply 7-21 oz/A per application, only 1 application per year. Apply as a broadcast application when the radish has reached the 2-leaf stage but before the 4-leaf stage. Temporary leaf injury may occur.
  • trifluralin (Treflan HFP): REI 12h, Group 3. Apply 1-1.5 pt/A per application, only 1 application per year. Apply and incorporate into the soil before planting. Rate based on soil texture and percent organic matter.

Postemergent Herbicides (after weeds germinate)

  • carfentrazone (Aim EC): PHI 0d, REI 12h, Group 14. Apply 0.5-2 oz/A per application. Do not exceed 6.1 oz/A per season. Can be applied with hooded sprayers to control emerged weeds. Prevent any spray from contacting the crop, or injury will occur. For best results, make application to actively growing weeds up to 4” tall and rosettes less than 3” across.
  • clethodim (Select Max): PHI 15d, REI 24h, Group 1. Apply 9-16 oz/A per application, up to 2 applications allowed per year, a minimum of 14 days apart. Do not exceed 32 oz/A per year. Apply to actively growing grasses. Add 0.25% v:v nonionic surfactant (1 qt/100 gal of spray). Can also be applied as a spot-spray by mixing 0.33-0.66% (0.44-0.85 oz/gal) Select Max and 0.25% v:v nonionic surfactant (0.33 oz/gal). Spray to wet, but do not allow runoff of spray solution.
  • glyphosate (Roundup Power Max): PHI 14d, REI 4h, Group 9. Apply 10 oz to 3.1 qts/A per application, multiple applications allowed per year. Do not exceed 5 qts/A per year. Rate based on target weed species. Can be applied during fallow intervals, prior to planting or transplanting, at planting, or before crop has emerged. Could cause injury when applied prior to transplanting or direct-seeding into plastic mulch. Remove residual product from plastic mulch with a 0.5” of water through irrigation or rainfall prior to planting.
  • pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0. Apply a 3-10% solution (3-10 gal/100 gal of spray). Apply in 75-200 gal/A of spray. Can use preplant, before crop emergence, or as a directed and shielded spray during crop growth. Avoid contact with foliage or crop damage may occur. Can also be used as a harvest aid and dessicant to remove leaves before harvest. Spray to wet, but do not allow runoff of spray solution.
  • sethoxydim (Poast): PHI 14d, REI 12h, Group 1. Apply up to 2.5 pt/A per application, only 1 application per year. Apply to actively growing grasses. Use with crop oil concentrate (2 pt/A) or methylated seed oil (1.5 pt/A). Crop oil can cause injury under hot and humid conditions. Can also be applied as a spot-spray by mixing 1-1.5% (1.3-1.9 oz/gal) Poast and 1% v:v crop oil concentrate (1.3 oz/gal). Spray to wet, but do not allow runoff of spray solution.
Weed Control