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2022 Midwest Vegetable Guide

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Onions and Related Crops – Diseases Midwest Veg Guide 2022 221 Fertilizing pH: Maintain a soil pH of 6.0 to 6.8 on mineral soils, and above 5.2 on muck soils. Garlic, Shallot–fall-planted: Before planting, apply 25 pounds N per acre, up to 150 pounds P 2 O 5 per acre, and up to 100 pounds K 2 O per acre based on soil test results and recommendations from your state. Sidedress in 20- to 40-pound increments of N per acre in 3- week intervals, ending 4 to 6 weeks before harvest. The total amount of N from fertilizer (including starter) and other credits should be 70 to 125 pounds N per acre. Onion, Leek, Shallot–spring-planted: Before planting, apply 70 pounds N per acre, 0 to 250 pounds P 2 O 5 per acre, and 0 to 250 pounds K 2 O per acre based on soil test results and recommendations from your state. Or, broadcast half the N and most of the K 2 O before planting, and at planting time band the remaining N, all of the P 2 O 5 , and up to 20 pounds of K 2 O at least 2 inches below and 2 inches to the side of the row. If indicated by soil test, include manganese, copper and zinc in band, or broadcast. If planting on organic (muck) soils with a pH over 6.0, include 1 pound manganese sulfate per 1,000 feet of row in the starter band (2 pounds actual manganese per acre), and/or apply 1 to 2 pounds manganese sulfate per acre as a foliar spray 2 to 3 times starting 3 weeks after emergence. Sidedress bulb onions with 90 to 100 pounds N per acre in mid-June or split that amount between early and late June. Sidedress green onions and leeks with 40 to 50 pounds of N per acre when the plants have four true leaves. Reduce the amount of fertilizer N applied by the value of N credits from green manures, legume crops grown in the previous year, compost and animal manures, and soils with more than 3 percent organic matter. The total amount of N from fertilizer (including starter) and other credits should be 190, 150, or 130 pounds N per acre for bulb onions, leeks, or green onions, respectively, on mineral soils, and 50 pounds less on muck soils. Harvesting Garlic and Shallot: Harvest when tops have fallen over and partially dried. Lift from soil and dry protected from sun and rain. After drying, trim roots and remove tops, or leave softneck garlic tops on for braiding. Onion, bulb: Harvest pungent storage-type bulb onions after tops have naturally fallen over, and tops are dried. To prevent sprouting of bulb onions in storage, use maleic hydrazide (Royal MH-30) according to label directions, when bulbs are fully mature and 50% of tops have fallen over but all tops are still green. Rolling leaves and undercutting several days before harvest can hasten dormancy and improve keeping quality of storage onions. Dig from soil and dry in field or indoors at 75°F to 80°F and 70 percent to 80 percent relative humidity. Cut tops about 1 inch from bulb at harvest or after drying, or braid tops and hang onions to dry. Clean dry onions by gently brushing. Time from seeding to harvest ranges from 100 to 125 days for pungent storage types. Harvest sweet onions at the desired size any time before tops dry down, as they do become pungent as they go into dormancy, but do not store as well as true pungent storage- types. Time from transplanting to harvest ranges from 60 to 80 days for cipollini or pearl-sized onions, or 90 to 115 days for larger sizes. Onion, green: Harvest by pulling from soil after bulb base is thicker than a pencil but before bulbing. Optional undercutting can be used to make pulling easier. Remove dirty outer layer from bulb area. Trim roots. Trim tops as needed if allowed by state regulations. Green onions are usually sold in bunches. Harvest small "knob" onions by pulling from soil when bulb has reached desired stage of development., following the same practices as for green onions. Time from seeding to harvest ranges from 60 to 70 days. Leek: Harvest when stalk is 1 inch or more in diameter. Undercut plants, pull from soil, trim, and bunch. The wide range of maturity times is variety-dependent. Some can withstand heavy freezes and mature late into the fall, while others are not as frost-hardy and mature earlier for summer harvests. Time from seeding to harvest ranges from 70 to 120 days. Onions and Related Crops – Diseases Reviewed by Dan Egel – Sept 2021 Recommended Controls Basal Rot of Alliums - Fusarium Fungus Non-Pesticide Garlic, Leek, Onion (Dry), Onion (Green), Shallot | Avoid fields with a history of the disease and excess water. Rotate to non-host crops for 4 years. Resistant varieties are available. Managing soil insect pests, like Onion Maggot, may reduce disease incidence.

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