Beet

Cornell Vegetables, 'Cercospora Leaf Spot of Table beet', vegetables.cornell.edu/pest-management/disease-factsheets/cercospora-leaf-spot-of-table-beet (fetched in-container 2026-09-02; read by the maintainer 2026-09-02): 'Rotate with non-host crops for at least 3 years'; 'Cercospora beticola can survive in the soil on infested plant residues for up to 3 years'; hosts 'Table beet, sugar beet, spinach, Swiss chard, lambsquarters, and pigweed.'

Penn State Extension, 'Cercospora Leaf Spot on Table Beets', extension.psu.edu/cercospora-leaf-spot-on-table-beets (fetched in-container 2026-09-02; read by the maintainer 2026-09-02): 'Beet growers wishing to prevent Cercospora leaf spot on their farm should implement a 3-year crop rotation featuring non-host crops'; 'Cercospora beticola can overwinter on host debris and in the soil for up to 3 years or survive on alternative weed hosts like lambsquarters and pigweed'; 'Cercospora leaf spot will infect spinach, Swiss chard, and sugar beets.'

UMass Extension, 'Cercospora Leaf Spot of Swiss Chard, Beets, and Spinach', umass.edu/agriculture-food-environment/vegetable/fact-sheets/cercospora-leaf-spot-of-swiss-chard-beets-spinach (fetched in-container 2026-09-02; read by the maintainer 2026-09-02): 'Rotate to non-host crops (outside of the Chenopodium family) for 2-3 years'; 'It can survive in the soil for up to two years.'

Univ. of Maryland Extension, 'Cercospora Leaf Spot of Vegetables', extension.umd.edu/resource/cercospora-leaf-spot-vegetables (fetched in-container 2026-09-02; read by the maintainer 2026-09-02): 'Don't plant susceptible crops in the same spot more than once every three years.'

UMass Extension, 'Spinach Downy Mildew', umass.edu/agriculture-food-environment/vegetable/fact-sheets/spinach-downy-mildew (fetched in-container 2026-09-02; read by the maintainer 2026-09-02): 'Rotate out of spinach for at least 3 years'; 'P. farinosa is capable of producing oospores, thick-walled structures which are capable of survival in soil.'

Cornell Vegetables, 'Spinach Downy Mildew', vegetables.cornell.edu/pest-management/disease-factsheets/spinach-downy-mildew (fetched in-container 2026-09-02; read by the maintainer 2026-09-02): 'Rotate out of land where spinach was grown for at least 2-3 years'; 'The pathogen can survive a few years in soil as oospores'; 'Oospores also could be left behind in soil after planting contaminated seed.'

Cornell Vegetables, 'Do Rotations Matter within Disease Management Programs?' (fetched in-container 2026-09-02; read by the maintainer 2026-09-02): its rotation table gives beet Cercospora leaf spot 3 years, beet root rots 3 years, spinach downy mildew and white rust 2 years.

University of Illinois Extension, 'Time Your Vegetable Plantings by Cold Hardiness' (2018-03-26), extension.illinois.edu/blogs/ilriverhort/2018-03-26-time-your-vegetable-plantings-cold-hardiness: very hardy vegetables 'withstand freezing temperatures and hard frosts without injury' (planted earliest in spring); frost-tolerant vegetables 'can withstand light frosts, but not freezing temperatures' (planted a couple of weeks later). LLM-summarised from a read of the page; it establishes the CATEGORIES but states no week offsets.

Colorado State Univ. Extension, GardenNotes #720, 'Vegetable Planting Guide', extension.colostate.edu/resource/vegetable-planting-guide (read 2026-07-25): hardy vegetables go in 'As early as 2-4 weeks before the date of the average last spring frost'; semi-hardy 'As early as 0-2 weeks before the date of the average last spring frost'; tender from seed 'around the date of the average last spring frost'; very tender 'Typically 2+ weeks after'. This is the source that states the offsets in weeks.

Where this rule sits in that range: hardy at 3 weeks is mid-range of CSU's 2-4. Half-hardy at 2 weeks is the EARLIEST EDGE of CSU's 0-2 - the most aggressive planting CSU sanctions, not the middle of it. The rule is inside published guidance at both ends, but it leans early on the half-hardy side and a gardener following it in a cold spring is taking that boundary.

Do not import an offset from another publication's hardiness scheme without checking the category names: CSU has no 'very hardy' tier, so a '4-6 weeks before frost' figure written against a four-tier scheme does not describe CSU's 'hardy'. Categories are not comparable across sources.