Herbicides: Correlation
Prices it moves with, and why
Herbicides such as glyphosate, glufosinate, 2,4-D and atrazine control weeds in crops. Prices depend on chemical inputs like phosphorus, chlorine and gas-based intermediates, on Chinese supply and on farm incomes, which set how much growers spend.
Proxy US PPI: agricultural and commercial pesticides and chemicals index (BLS base period =100) · monthly, Jan 2006 to Sep 2026There is no free public price for herbicides itself, so this tab uses the closest public series as a stand-in. Read the numbers as an indication, not as the price of this exact item.
What its price moves with
Selected linkHerbicides and Phosphate rock
Monthly changes 0.17 little or none correlation 12-month changes 0.52 moderate correlation Last 5 years 0.30 monthly changes Lead or lag none No clear lead or lag Price function, Jan 2006 to Sep 2026 Herbicides ≈ 61.9 × (Phosphate rock)0.15 R² 0.41 On this fit, a 10% higher phosphate rock price goes with a 1.4% higher herbicides price over the long run. Units: index (BLS base period =100) and $/mt.Chart: Herbicides and Phosphate rock prices rebased to 100 at Jan 2006, log scale
Both prices rebased to 100 at Jan 2006, on a log scale so equal percentage moves look the same size.Chart: Herbicides price against Phosphate rock price, monthly, log scales, with fitted line
Each dot is one month; paler dots are older (2006), darker dots recent (2026); the ringed dot is the latest month. The dashed line is the fitted price function. Both axes are logarithmic.Glyphosate contains phosphorus, made from phosphate rock via energy-hungry yellow phosphorus. Against the pesticides proxy, monthly moves correlate at 0.17, yearly moves at 0.52 and 0.30 over the last five years.
little or none co-movement month to month · 249 months Show chartsGas-based chemicals such as ammonia, methanol and hydrogen cyanide feed glyphosate and other herbicide intermediates. European gas correlates at 0.00 for monthly moves but 0.58 for yearly moves, showing slow cost pass-through.
little or none co-movement month to month · 249 months Show chartsMany herbicides, including 2,4-D and atrazine, are chlorinated molecules. Against the chlor-alkali proxy, monthly moves correlate at 0.17 and yearly at 0.74, with the best fit having the pesticides index lead by about 3 months.
little or none co-movement month to month · 249 months Show chartsMaize growers are big herbicide users, and maize prices shape farm income and planting decisions. Monthly moves correlate at only 0.03 and yearly at 0.29, as herbicide prices are set seasonally on distributor contracts.
little or none co-movement month to month · 249 months Show chartsHerbicide-tolerant soybeans in the Americas use large amounts of glyphosate and other herbicides. Even so, monthly moves correlate at 0.01 and yearly at 0.18, since farm demand changes slowly and prices are set before each season.
little or none co-movement month to month · 249 months Show chartsPotash and crop protection are bought by the same farmers and both follow the farm income cycle. Monthly moves correlate at 0.24, yearly at 0.61 and 0.53 over the last five years, a common farm-input driver rather than a shared material.
weak co-movement month to month · 249 months Show chartsHow to read these numbers
Correlation of monthly changes (the number in the coloured pill) compares how much each price moved, month by month, since 2006 or the first month both series exist. It runs from −1 to +1: near +1 the two usually rise and fall in the same months, near 0 there is no link, and a negative number means they tend to move in opposite directions. Above 0.7 is strong, 0.4 to 0.7 moderate, 0.2 to 0.4 weak.
12-month changes compare year-on-year moves, which shows whether two prices share the same cycles even when the month-to-month noise differs.
Price function is a straight-line fit of the two prices on logarithmic scales: price ≈ k × (partner price)β. β is how much this price moves, in per cent, for a 1% move in the partner over the whole period, and R² is the share of the variation the fit explains. Two prices that both drift up with inflation can fit well without any real link, so read it together with the monthly correlation.
Lead or lag checks whether the monthly correlation is clearly higher when one price is shifted by 1 to 6 months.
Correlation is not cause. The reasons on each card explain the economic link; the numbers show how strongly it has shown up in prices. Proxy series are US producer price indexes or related prices and can blur the real link.
Data: World Bank Commodity Price Data (Pink Sheet), October 2026; US Bureau of Labor Statistics producer price indexes, IMF primary commodity prices and US EIA prices via FRED, Federal Reserve Bank of St. Louis, retrieved November 2026. Calculations by this site.