Author
John J. McHugh, Jr. and Ronald F. L. Mau
Department of Entomology
Honolulu, Hawaii
Disease |
Control Measure(s) |
Comments |
| Angular leaf spot | Resistant varieties
(cucumbers). Copper hydroxide (Kocide DF or Champion WP) at 2 to 3 lb. per acre. See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
Check with seed dealers for
resistant cucumber varieties. Cool, rainy conditions favor disease. Treat at first sign of symptoms. 0 day PHI. |
| Anthracnose | Resistant varieties
(cucumbers). Crop rotation with non-cucurbits. Chlorothalonil (Bravo, Terranil) at 2 to 3 pt. per acre (F flowable products) or 1.5 to 2.5 lb. per acre for dry formulations (DF, DG) OR mancozeb (Dithane, Manzate, Penncozeb or Manex II) at 2 to 3 pt. per acre for flowables or 2 to 3 lb. per acre for dry products (WP, DF, DG). See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
Check with seed dealers for
resistant cucumber varieties. Disease favored by warm, wet weather. Avoid overhead irrigation. Apply fungicides at first sign of disease symptoms. 0 day PHI for chlorothalonil; 5 day PHI for mancozeb. Note: chlorothalonil is phytotoxic to mature watermelon fruit. |
| Downy mildew | Resistant varieties
(cucumbers). Metalaxyl/chlorothalonil (Ridomil Gold/Bravo) at 2 lb. per acre at 14 day spray interval OR metalaxyl/mancozeb (Ridomil Gold MZ) at 2.5 lb. per acre OR Chlorothalonil (Bravo, Terranil) at 2 to 3 pt. per acre (F flowable products) or 1.5 to 2.5 lb. per acre for dry formulations (DF, DG) OR mancozeb (Dithane, Manzate, Penncozeb or Manex II) at 2 to 3 pt. per acre for flowables or 2 to 3 lb. per acre for dry products (WP, DF, DG). See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
Check with seed dealers for
resistant cucumber varieties. Disease favored by moist conditions (rain, dew, overhead irrigation). Treat at first sign of disease. 0 day PHI for metalaxyl/chlrothalonil and chlorothalonil; 5 day PHI for metalaxyl/mancozeb and mancozeb. Note: chlorothalonil is phytotoxic to mature watermelon fruit. |
| Fusarium wilt (watermelons) | Resistant varieties. Crop rotation with non-cucurbits. |
Check with seed dealers for resistant watermelon varieties. In Hawaii, Sangria is a commercially grown hybrid with Fusarium wilt resistance. |
| Gummy stem blight | 2 to 3 year crop rotation
with non-cucurbits. Benomyl (Benlate) at 0.25 to 0.5 lb. per acre OR chlorothalonil (Bravo, Terranil) at 2 to 3 pt. per acre (F flowable products) or 1.5 to 2.5 lb. per acre for dry formulations (DF, DG) OR mancozeb (Dithane, Manzate, Penncozeb or Manex II) at 2 to 3 pt. per acre for flowables or 2 to 3 lb. per acre for dry products (WP, DF, DG). See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
Disease most severe during
rainy season. Watermelons are the most susceptible to Gummy stem blight. First symptoms appear at the soil level on the plant crown. Fungicides best used as a preventative measure where Gummy stem blight is known to be a problem. 1 day PHI for benomyl; 0 day PHI for chlorothalonil; 5 day PHI for mancozeb. Note: chlorothalonil is phytotoxic to mature watermelon fruit. |
| Measles | Reduce irrigation. | Wet soils/excessive moisture
necessary for measles to occur. Prevalent on heavy clay soils. |
| Nematodes (root-knot and reniform) | Pre-plant injection with
metam sodium (Vapam 42%) at 30 to 60 gal. per acre. Check
with manufacturer for recommended injection methods. See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
Use at highest rate in fields where nematodes are known to be a problem. Do not transplant before 21 days after treatment. |
| Powdery Mildew (Sphaerotheca fuliginea) | Myclobutanil (Rally 40W) at
0.25 lb. per acre. Section 18 Specific Exemption for use in Hawaii on watermelon only. See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
Disease favored by warm,
humid conditions. 2 day PHI. |
| Silverleaf (zucchini and summer squash) | Exclusion of whiteflies by row covers. | This disorder is caused by the feeding of the silverleaf whitefly. |
| Vine decline (Monosporacsus, Phytophthora, Pythium) | Pre-plant injection with metam sodium (Vapam 42%) at 30 to 60 gal. per acre. Check with manufacturer for recommended injection methods. | Use at highest rate in fields where vine decline is known to be a problem. Do not transplant before 21 days after treatment. |
| Virus diseases (Zucchini yellows mosaic, watermelon mosaic, papaya ringspot-W) | Avoid planting downwind of
cucurbit crops. Do not work from old plants to young plants. |
Vectored by aphids and also
mechanically transmitted. Avoid transplanting of cucurbits immediately after harvesting operations. |
Insects/Mites |
Control Measure(s) |
Comments |
| Aphids (various species) | Conserve natural enemies. Endosulfan (Thiodan 3 EC) at 0.67 to 1.33 qt. per acre or Thiodan 50W at 1 to 2 lb. per acre. Do not exceed 3lb. active ingredient per acre per year. Methomyl (Lannate 90) at 0.5 to 1 lb. per acre or Lannate LV at 1.5 to 3 pt. per acre. See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
By limiting chemical
insecticide use predators and parasites can help control
aphid populations. 2 day PHI for endosulfan; 1 day PHI for Lannate 90 and Lannate LV at low rate, 3 day PHI for high rate. |
| Leafminers (vegetable and serpentine leafminers) | Conserve natural enemies. Abamectin (Agrimek) at 8 to 16 oz. per acre. See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
By limiting chemical
insecticide use parasites can help control leafminer
populations. Abamectin minimally impacts natural enemies. |
| Melon fly | Sanitation. Trap cropping and baiting with 1% Nu-lure + 1% Malathion at least twice weekly. |
Destroy all crop residue,
bury cull piles. Plant trap crops as windbreak rows (e.g. sterile sudax grass) spaced 45 ft. apart. Do not spray crop for fruit flies. |
| Melon thrips (Thrips palmi) | Abamectin (Agrimek 0.15EC)
at 8 to 16 fl. oz. per acre. See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
Best control achieved at first sign of melon thrips infestation (immature thrips are much easier to control). |
| Silverleaf whitely | Imidacloprid (Admire 2F) at
16 oz. per acre.
See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
Soil apply imidacloprid
through drip irrigation system over a 2 hour period.
Application timing based on label prescribed thresholds
and days after transplant. Do not apply more than 32 fl. oz. of Admire per acre per year. Check label for plant back restrictions. 21 day PHI. Aphid control is excellent when using Admire 2F for silverleaf whitefly. Helps in limiting field-wide establishment of aphid-vectored virus diseases. |
| Spider mites | Abamectin (Agrimek 0.15EC)
at 8 to 16 fl. oz. per acre OR dicofol
(Kelthane 50 WSP) at 1.25 lb. per acre. See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
7 day PHI for abamectin; 2 day PHI for dicofol. |
Control Measure(s) |
Rates |
Comments |
| Glyphosate (Roundup Ultra WS) or Paraquat (Gramoxone Extra 2.5E) | Roundup Ultra WS at 0.5 - 10
pt. per acre (higher rates for difficult to kill weeds,
for example, purple nutsedge). Gramoxone Extra 2.5E at 1.5 to 3 pt. per acre. |
Stale seedbed treatments. Allow at least 3 days between application of Roundup Ultra WS and planting. |
| Bensulide (Prefar 4-E) +
naptalam (Alanap-L) See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
5 to 6 qt. per acre for Prefar 4-E tank mixed with Alanap-L at 6 to 8 qt. per acre. | Preplant
incorporated/Preemergent. Broadleaf + grass weed control. |
| Paraquat (Gramoxone Extra 2.5E) | 3 pt. per acre plus 0.125%
nonionic surfactant. Use shielded spray rig. |
Post-plant/Postemergent/Directed
spray. Broad spectrum weed control. 30 day PHI. |
| Sethoxydim (Poast 1.5EC) See Hawaii Pesticide Information Retrieval System for Information on cucurbits |
1 to 1.5 pt. per acre plus 0.125% nonionic surfactant. | Pos-plant/Postemergent/Broadcast
spray. Grass control. 20 day PHI. |